For anyone who is interested in first kills, WowInsider has posted an article listing statistics on Guild first kills in Cataclysm, and the gear level that they had when they did it:

http://wow.joystiq.com/2011/01/03/a-sur ... lysm-raid/

To be honest I felt the list was quite encouraging.
Looking at this, it seems you don't need uber-levels of gear to start downing things.

That's not to say that people shouldn't have the best gear possible of course, but I think it hints that we're definitely ready for raiding.

The interesting question is why the 10-man ilvl was higher for those first kills.

Was it because the encounters are actually harder on 10-man and require better gear to do?

Or because it is easier to kit out 10 players in heroic gear than 25, so the 10-man raids were either 10-man guilds who hit the heroics hard or 25-man guilds fielding their 10 best players, whereas the 25 man kills had to "make do" with some players that hadn't spent as much time/effort gearing up?

I think it's a mixture of both.

For your first kill you'd probably want your strongest team to learn the fight and get it down, and your 10 strongest players are going to be on average stronger than your 25 strongest.

But there are some things that make 25 player easier; for example you get 3 rebirths/reincarnations/soulstones rather than 1, and it's less punishing if one person makes a mistake as there are more people there to compensate.

I still think its just a blizz faliure to balance things.

25 mans has a lot more raid buffs and group synergy, thus lower ilvl demand.

The encounter I guess lacks a bit o balance between 25 and 10