Matt Tieger has stated on the Playstation Blog that PS3 users will probably get some type of beta or demo before the August 28th release of Fall of Cybertron. This will probably be for online multiplayer rather than campaign because I'm guessing they want to save the campaign stuff for the actual release. So, it looks like some of us might get to make our own custom Transformers before August 28th. No actual date is set yet and it is unknown whether XBOX users will get the same treatment.
"We are talking multiplayer features for all you PSN players, and you might even see something playable on PSN before the game launch….but more on that at a later time."