Joystiq caught a (now private) Twitter message from an account belonging to EA's UK public relations team that says it all: "EA LOS ANGELES ANNOUNCES THE DEVELOPMENT OF COMMAND & CONQUER 4." The catch is that the link posted with the message doesn't actually point to a page that has that press release on it and EA isn't talking about it. So is there going to be a Command & Conquer 4 announcement soon? Yeah, probably.
The other part of the puzzle is that GameSpot started running a Command & Conquer retrospective yesterday. Those multi-day retrospective features they do around a series or franchise seem to always lead into the announcement of a new game in the series. So my guess is that they'll end up with some sort of exclusive announcement or details on C&C4 in the relatively near future.
You might also remember that an online survey went around recently talking about "MMORPG like player progression" and other persistent features for the next Command & Conquer game. So EA certainly seems to have C&C on the brain at the moment, even if all that MMO-type stuff sounds sort of crazy. I don't know, even if it's taking an entirely different direction, C&C3 is still only a couple of years old. When that game was announced, I was all excited about the return of Kane and the return of the C&C franchise. But considering we've seen C&C3, C&C Red Alert 3, and an expansion for each over the last couple of years, it feels like it's a little soon to be announcing yet another game.