This is one of those questions that could have a really, really long answer that potentially includes a lot of numbers and formulas. For my sanity (and possibly yours) I'm going to simplify it.
No, not all items are made equal. This is because not all stats have the same 'cost' on items. One really big example here is Stamina. Stamina costs less than any other pure stat on gear. You can get a fairly large amount of it for a relatively low cost, compared to something like Strength. Moreover, the rating conversions are not the same across all stats, which could cause even more strange item results. The Armor Penetration rating required to get 1% penetration would cost more of the item budget than the crit rating required to get 1% crit. Note, those stats and numbers are just examples that I pulled out of thin air, so please don't take them as law.
On top of that, stats on items have a sort of diminishing return. The higher a single stat stacks on an item, the higher the cost of that stat. So an item that has only Agility on it would have fewer total stat points on it than an item with Agility and Strength, for example.
So there are a lot of factors that can determine what item is the 'best' for its iLevel. A lot of different things come into play when itemizing. Wowwiki has a pretty good guide to the whole spiel if you want to dig deeper. If you want even more than that, just search around Elitist Jerks. You'll find more on it than you could ever possibly want, most likely.
Bob Dewane asked...
"Has ther been any word as to whether or not Blizz will use the "gate" system again in Ulduar to control raid progression? I know it caused a ton of controversy in Sunwell."
We've seen no indication of this on the PTR. This doesn't mean it can't be plugged in at the last minute without anybody knowing, but I quite seriously doubt that they would pull something like that. I don't think we'll be seeing anything like those gates in Ulduar.
"What happens if you queue for a battleground as a group, does everyone appear post-BG back where they were when they went in, or back where the leader was when he/she went in?"
They go back where they were when they entered the battleground, no matter who queued them up or where the party leader is in the world. Everyone goes back to their own original location.
"Are we ever going to see 'Know Your Lore' again?"
Yes, absolutely. I got burned out writing it while trying to keep up with all of the new revelations and bits of info that Wrath of the Lich King was providing, so I just took a break from it for awhile. I know I disappointed a lot of people by doing so, but I think some cases no column is better than a bad column, and I personally think this was one of those cases.
I'm going to be working with a couple of the other writers to bring it back soon.
"Did Blizzard ever actually remove the requirements for old instances, like the Seal to get into UBRS or the Aqual Quintessence for Molten Core, etc?"
In most cases, yes, those things were removed. You don't need a Seal for UBRS anymore, and it can be solo'd. The Quintessence isn't needed for Molten Core, either. The runes by each boss are extinguished automatically when a boss is killed, you don't need to touch it.
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