I'm shocked, shocked to learn that the bullshit TOY STORY 4 rumor is bullshit.
For those of you who don't hang around the Twitter pool hall, a Colombian radio host named Jorge Luis Balaguera "confirmed" via tweet that Tom Hanks, Tim Allen and Joan Cusack would be returning for TOY STORY 4. The first red flag was the reported 2015 release date. That's when Pete Docter's INSIDE OUT is scheduled (and Pixar is a one-movie-per-year outfit). The second red flag: Pixar isn't exactly a leaky ship. I can't think of the last time a non-trade broke a major Pixar story. Typically, when the studio has something to announce, they do it via press release or a splashy unveiling at Comic Con or D23.
In any event, HitFix's Drew McWeeny did some sniffing around, and he must've received an off-the-record denial from someone at Pixar (which is as good as we're going to get, since studios generally don't like to officially debunk every rumor that bubbles up in the media). As of right now, TOY STORY 4 is not in development. No one is working on it. And while Pixar has gotten dispiritingly sequel-happy of late (what with MONSTERS UNIVERSITY and FINDING NEMO 2 on the way), I think the studio would have to hit a very rough patch for TOY STORY 4 to happen. This would be the first "very rough patch" in Pixar history, so don't hold your breath.