The way the Playstation Vita looked at E3 might not be the final design, after all. According to Andriasang (citing an interview in Famitsu) the buttons and the analogue sticks might still be moved around. Sony have supposedly been in talks with various developers about the potential placement of the various parts of the machine. Either way, we're probably not talking about any major overhauls.
There were plans to scrap the touch screen on the back of the Playstation Vita because of cost-issues, but it will stay in anyway. From what we experienced with the machine at E3, the current design worked pretty well for the games we had time to test - see us play Uncharted: Golden Abyss on GRTV for an example of the Vita in action.