TS4 is being developed by Free Radical Design. Currently we know very little about it though, and it appears it will be quite some time before we will actually be seing screesnhots, but it'll be worth the wait.

Since TS is personally my favorite fps series of all time (Future Perfect being my favorite) I can't wait to here more news about this game, so if I learn anything, I'll post it here, and if you know anything new, post it here.

Several magazines have talked about the game, and there is an official teaser trailer.

Teaser Trailer
















Links
Free Radical Design
Timesplitters4.net