It ws announced a few days ago by The 4400 creator and producer Scott Peters that the show has been cancelled by the USA Network, most likely due to slumping viewers ratings. I liked this show - it wasn't my favorite but I looked forward to it. I hate that they're ending it with some many unresolved storylines.
USA also cancelled The Dead Zone, which I'm personally not sad about.
In addition to a couple of new shows on the USA lineup, the only definites for new seasons are Burn Notice and The Starter Wife, both of which I don't watch. It seems a 3rd season of Psyche is likely, but because negotiations with Tony Shalhoub were cut short by the writer's stirke, it is unclear whether there'll be another season of Monk.