Paramount might not have confirmed it, but Michael Bay kinda has on his Blog, but for 2012, not 2011... Apparently he's agreed to July 4th 2012 so he can have a year off, so Paramount (or the trades sources) screwed up on the release date.

Even though Paramount Pictures and DreamWorks are not yet ready to confirm the development of Transformers 3, the studios are still willing to lock in a potential release debut for a third installment in their franchise, with the trades passing along that they have set up July 1, 2011 as the day for it to launch into theaters.
They cautioned that they are not formally announcing another sequel yet but rather claiming stake for that holiday weekend should they choose to. At the current time, there is no competition for that weekend.
Paramount likewise moved their co-produced adaptation of Marvel's Thor up a few weeks to May 20, 2011. The previous date was set at June 17, 2011. So that means two comic adaptations in May of 2011, with Spider-Man 4 set to hit on May 6th.
Update: As Maniac Middlerealm says below, there seems to be some confusion between Paramount and Michael Bay on when production will begin for a potential Transformers 3. While the trades were passing along Paramount and DreamWorks' press release, director Bay quickly responded on his forums that the date was wrong.
I said I was taking off a year from Transformers. Paramount made a mistake in dating Transformers 3 - they asked me on the phone - I said yes to July 4 - but for 2012 - whoops! Not 2011!!! That would mean I would have to start prep in September. No way. My brain needs a break from fighting robots. -- Michael
It seems likely that Paramount and DreamWorks will give Bay a year off. We won't know until the new date is confirmed but expect the third installment on the July 4th holiday in 2012. Not 2011.
Paramount might not have confirmed it, but Michael Bay kinda has on his Blog, but for 2012, not 2011... Apparently he's agreed to July 4th 2012 so he can have a year off, so Paramount (or the trades sources) screwed up on the release date.
Yeah I think 2012 would be a better release date. There is just too much competion in the summer of 2011, what with Spider-Man 4, Thor, and Captain America.
I still think that Marvel fans everywhere (and the stars of Spider-Man) need a break from the wall-crawler. I'm eagerly awaiting the releases of Thor, Captain America, and The Avengers.
Trans 3 should do the Unicron story.. I would be massive but cool if they can pull it off.
Chris are u kidding me? summer 2011 is more than 2 years away. Thats more than enough of a break (those lazy actor bitches).
Personally i dont care how much competition there is or how much each movie makes. I just want a feast of comic movies to watch over and over and over. 2 words..... "Theater Hopping" baby!!!!!
Wow VIOlator, I thought I was the only one who remembers having a reason to theatre hop. The days when a movie company kept the movies in theatre till their next major release. I would love to See Thor, Spider-man and whatever the same day. I'll spend 12 hours in a theatre, I have before. One time was when Transformers The Movie First came out. Man, I still love that theme song.
MidNightFan, they're waiting on Nolan before they start announcing things for Batman. He hasn't even officially signed on yet, nor is there a script in place. So any of these stupid casting rumors you hear at this point are just BS.
Hey Warner Bros? Where's Batmans release date? Transformers 3 is already being scheduled, and the 2nd film comes out in June of 2009. Its time to speed things up! Who feels the same way?
-MidNightFan