We already knew that today was the big day for T-Mobile's Galaxy S II to receive Ice Cream Sandwich. T-Mobile has just let on that the rollout will begin tonight at 11pm EST. The update will be done via Kies, so unfortunately the update won't be showing up over the air. Hope you've got a microUSB cable handy.
The update is just slightly behind the 4.0.4 that other devices have been receiving, but users probably won't be complaining too much.