Sony/Columbia pictures has announced to the LA Times that Spider-Man's 4th theatrical appearance will be in May 2011.
Producer Laura Ziskin says that 4 years os plenty of time to get a script ready and the movie shot. Despite the announcement, neither director Sam Raimi or the stars of past installments have signed on, and there have been rumors floating around the net that a new cast and crew is imminent. That rumor started just after the news was that Spider-Man 4 and 5 would be filmed together.