Ok these are the tenative tiers based on PO usage, and smogon bans, this is most likely subject to change, since smogon didn't make these directly, but I doubt it'll change too too much.
February 2011 UU Tiers
The official tiers for the month of January (the cut-off between OU and UU being 4%):
DW Overused:
Stats found here
WiFi OverUsed
Blaziken
Blissey
Borutorusu
Breloom
Burungeru
Charizard
Cloyster
Doryuuzu
Dragonite
Electivire
Espeon
Forretress
Garchomp
Gengar
Gliscor
Gyarados
Heatran
Hippowdon
Infernape
Jirachi
Jolteon
Kingdra
Latias
Latios
Lucario
Ludicolo
Machamp
Metagross
Nattorei
Ninetales
Ononokusu
Politoed
Randorosu
Rankurusu
Roobushin
Rotom-W
Salamence
Sazandora
Scizor
Shandera
Skarmory
Starmie
Swampert
Tentacruel
Togekiss
Tyranitar
Urugamosu
Vaporeon
Zapdos
Zuruzukin
+Borutorusu
+Rotom-W
+Shandera
+Zuruzukin
-Venusaur
Stats found here
In DW, Blissey and Mamoswine dropped to UU and Ludicolo became OU. In Wifi, Voltolos, Rotom-W, Shandera and Zuruzukin became OU, while Venusaur fell to UU.
Seeing Shandera OU in Wifi give thoughts on only banning it with Shadow Tag in DW, instead of banning it completely... Also Terakion is on his way to Wifi OU, so beware!
Surprising that Wifi OU increases in size while DW doesn't. Well, anyway, enjoy the new UU tiers! Maybe next month we'll add NU too, but it's too early now
link: http://pokemon-online.eu/forums/showthread.php?4293-February-2011-UU-Tiers