This information is pretty hard to come by. I've scanned here, wow offical forums, and numerous other wow related sites. Having no L90 in the beta, I can't check myself. The loot drops are pretty easy from data mined items.
This is what I know regarding the ilvl for drops
Senarios - 463 (rares)
L90 5-mans - 463 (rares) 476 (epic - last boss)
LFR 476-483 (No tier in 1st raid. Half a tier lower for 1st raid?)
Valor vendors - 489
Rep vendors - 496
iLvl Entry requirements
Senarios - No idea. A guess would be 450
L90 5-mans - No idea. Same guess of 450
LFR - I know that beta testing has normization to 463, but this seems too high for entry ilvl, given it's the same as the drops from 5-mans/senarios, thus requiring a complete 100% set of 463 gear. (There are always a couple of slots which you just can't get a drop for)
Anyone know the actual iLvl entry requirements for MoP Senarios, L90 5-mans and LFR?