Patch 4.1 looks likely to drop any week now, so now's a good time to find out what the patch can do for you, gear-wise. The two new dungeons, Zul'Aman and Zul'Gurub, appear to have been completely itemized, so we can probably feel relatively safe in looking at the gear that drops from them. The gear is all ilevel 353, which puts it below raid and valor point gear but above most current heroic dungeon drops. Therefore, casual raiders, non-raiders, and new level 85 death knights will probably find a lot to like in the stuff coming out of this dungeon. Let's take a look at the gear.
For the most part, these will be clear upgrades over your ilevel 346 heroic options, but in cases where there's a better or competitive old heroic option, I will mention it. Note that this information is from the patch 4.1 PTR and may therefore change when the dungeons go live.
Reforged Trollbane is a 2H axe with mastery and hit rating. This, of course, makes it a great choice for orcs. The secondary stats are also nearly perfect for tank death knights. You can simply reforge the hit rating into whatever secondary avoidance stat you need more of.
Jeklik's Smasher is a 2H mace option, making it especially useful for humans and dwarves. It uses mastery and critical strike rating, making it especially nice if you don't need the hit rating on the Reforged Trollbane.
The Zulian Slasher marks the return of the novelty of having a wielded skinning knife weapon. It also has the relatively useful hit and critical strike ratings. It's a sword, so it'll provide some extra expertise to gnomes and humans.
Renataki's Soul Slicer is another 1H option and has expertise and mastery. Like the slasher, gnomes and humans can take advantage of some extra expertise with racials.
The Roaring Mask of Bethekk is your DPS upgrade and provides haste and critical strike rating. The red socket also means you essentially get another free 30 critical strike rating when you throw in a strength gem.
Your tank option is the Spiritshield Mask. One nice thing about this helm is that it avoids "wasting" itemization on hit and expertise like most ilevel 346 helms do. Instead, it has dodge and parry rating. You can just reforge whichever one of those you need less into mastery and be good to go.
The Amulet of Protection is your tanking option here, with dodge and mastery rating making it a pretty amazing choice. There is no DPS neck option for death knights out of the new dungeons, possibly because Blizzard figures we can just grind exalted Ramkahen and grab the Gift of Nadun.
Skullpiercer Pauldrons are your DPS shoulders. They have critical strike and mastery.
Pauldrons of Sacrifice are your tank option. Parry and mastery make these very well itemized for a death knight tank.
The Hex Lord's Bloody Cloak has haste and mastery, making it especially nice for DPS death knights.
The Spiritguard Drape is your tank option, and while it isn't a bad cape at all, you'll probably want to stick to the Wrap of the Great Turtle from exalted Guardians of Hyjal reputation, if only for the mastery.
The Chestplate of Hubris is your DPS option for the chest and is actually incredibly competitive with the Elementium Deathplate, thanks to the presence of two gem slots. It'll probably come down to which secondary stats your chosen spec values more as to which of them is better for you.
The Battleplate of the Amani Empire is your tank option. The presence of two gem slots means, once again, this is incredibly competitive with the BoE blacksmithing ilevel 359 option, the Hardened Elementium Hauberk. The one that's right for you may come down to whether you need dodge or parry rating more, though there's no shame in just grabbing the cheaper option at this level.
Deathcharged Wristguards are your DPS option. Alpha Bracers are surprisingly competitive with these thanks to their gem slot and mastery, but if they refuse to drop for you or if you need more expertise, Deathcharged Wristguards are still a pretty nice second option.
The Amani Armguards are your tanking option. Again, the gem slot and mastery on Alpha Bracers means they're pretty competitive here for tanking too, and the Sandguard Bracers from exalted Ramkahen will also edge these out. If you can't get either, though, the Amani Armguards are a nice stopgap. You'll probably want to reforge the expertise to mastery.
Plunderer's Gauntlets are your DPS option. They contain haste and expertise, so if you don't need the expertise, you could find them not as a good as they could be. Luckily, tier 11 gloves are relatively cheap to purchase, so you'll replace them pretty quickly if you keep running your seven heroics a week.
Bone Plate Handguards have parry and dodge. If you're looking to stack more mastery, some of the ilevel 346 might be better in theory. But avoidance is still pretty prime, and you'll get slightly more stamina off these gloves, so you may want to consider fitting them in anyway. Regardless, tier 11 gloves are pretty cheap and easy to grab, so it's not a huge deal.
Coils of Hate is a pretty nice plate tank belt containing mastery and dodge. The Hardened Elementium Girdle is still better, but if you want to save some money, Coils of Hate will do you until you can get a raid drop. There's no DPS belt option from the new heroics, probably because you can just grab the Belt of the Ferocious Wolf from exalted Guardians of Hyjal for that.
For DPS legs, you'll get Jungle Striders. If your spec doesn't need expertise (or you're already expertise soft-capped), these legs can be a bit less valuable than they first appear.
With parry and mastery, Legguards of the Unforgiving will serve you well as a tank until you can pick up your tier 11 legs.
You can pick up Skullcrusher Warboots for your DPS needs. Mastery and hit rating means this should be a pretty decent choice for any spec, assuming you need that hit rating (or what hit rating you can't reforge away). In what should be a pretty predictable pattern by now, there's no tank boot option because you can pick up some epic boots from exalted reputation with your Twilight Highlands faction.
Ring of the Numberless Brood features both haste and mastery rating, making it a pretty great option for DPS death knights.
Band of the Gurubashi Berseker has hit and expertise rating, meaning it's going to be great if you haven't hit those soft caps yet and mostly lackluster if you have. Still, if you get one to drop, it does have superior strength to previous heroic options, so you may want to play around with reforging to fit it in.
Talonguard Band is your tank option. The presence of expertise makes it less desirable than it could be due to the general dislike of expertise and hit rating among death knight tanks these days. If you don't need the threat from expertise, you may want to consider sticking with Elementium Moebius Band and Felsen's Ring of Resolve.
The Miniature Voodoo Mask is frankly a novelty, unless those gnomes end up doing nuclear bomb-level damage. Still, you get to summon gnomes at your beck and call, and who doesn't love that? If you aren't a fan of gnomes, consider it a chance to watch three gnomes writhe under your unholy control before dying horribly every 10 minutes. Either way, you win. Grab this one for the fun of it and pull it out for parties and trivial content raid nights with the guild.
Learn the ropes of endgame play with WoW Insider's DK 101 guide. Make yourself invaluable to your raid group with Mind Freeze and other interrupts, gear up with pre-heroic DPS gear or pre-heroic tank gear, and plot your path to tier 11/valor point DPS gear.