It only counts towards the 'big four' of Northrend as far as I can see. Those reputations are: The Kirin Tor, The Argent Crusade, The Knights of the Ebon Blade, and the Wyrmrest Accord. You should be able to get really, really high reputation with the Valiance Expedition/Warsong Offensive just through questing, but I wouldn't be surprised if we saw a Tabard for them soon, too. The little people like the Kalu'ak are, so far, not included in this system.
Read on for more answers to your questions!
Bhubba asked a pair of questions...
Are there any items similar to "Everlasting Underspore Frond"? It was immensely helpful while leveling in Outland, and I was hoping for another version, or one at level 80 (the Frond isn't as helpful at 70 as it was leveling).
I haven't seen anything like this so far, no. If it's any consolation, pretty much everything that you could count as an animal in Northrend has a chance to drop some meat that you can cook. So skill up your Cooking, and you'll have a much easier time on the food side of things!
With the change to mounts and pets, once you "train" them, do they tell you if you already have learned them, such as with other similar items? God forbid in my quest to get all the mounts I can, I waste gold buying ones I already have.
Yes, the item tooltips will say "Already known" or something along those lines on them in red text.
I plan on getting the "Leading the Cavalry" achievement sooner or later, and for that I may level my faction cities to exalted. Do we get any significant amount of reputation with them while leveling in WotLK? Or should I start now, before the rush on runecloth for the titles?
Start grinding out that rep. I haven't seen any gains with capital cities in Northrend yet. Cenarion Expedition is the only old rep I've seen gains towards, as a commenter mentioned, due to DEHTA. Start turning in Runecloth and running Alterac Valley. You'll need it.
I have a question- and this is probably the wrong place to put this but... Is the skill-level necessary to start in WoTLK going to be the next step up from the skill-level necessary to beat the last run, i.e Sunwell? To dumb it down so even I dont get confused: will you be able to start WoTLK in TBC greens or are you going to need to get all the top tier stuff just to stay alive?
The first Northrend dungeons can be run in greens, yep. You don't need to have done Sunwell to be useful in Northrend. However, if you have done Sunwell, a lot of things are going to be dramatically easier. Even if your gear is somehow below what the opening dungeons are meant for, you can run some Northrend quests and the quest rewards will bring you up to speed.
I had a question about the new mana regen mechanics. Does the Replenishment buff stack? As in, if you have a group with a SPriest and a Survival Hunter, and Both activate it at the same time, do you get a stacking buff at all? Two unique buffs? Do they stack at all?
Replenishment doesn't stack at all. If multiple people are using Replenishment, the buffs would just overwrite eachother as things trigger it.
I'm wondering about raid content progression. Are most guilds planning to split teams and gear up in 10-man versions or does it seem feasible to go straight to the 25-man version?
You can start out in 25-man content once you're raid level, but it's a bit more gear demanding. You can start 10-man raids pretty darn quick after you hit level 80, but the 25s will require more time spent gearing up in normal dungeons and heroics as far as I can tell. It's only a difference of waiting a week or two more, not that big of a deal. You don't need to do any 10-man content before starting 25-man content if you don't want to do that. A lot of guilds seem to be planning to do both to speed up gearing themselves up, but it's not a mandatory thing.