Whilst I was away from my desk, an e-mail went out to those of us who attended the TMNT fan event last week, allowing us to talk about what we saw.
Since Rose (of the NinjaPizza blog) totally beat me to the punch by a mile on this one anyway, I will defer you to her masterful write-up rather than hold up the flow of information from you any longer!
http://ninja-pizza.blogspot.com/2011/04/nickelodeon-tmnt-fan-preview-event.html