My understanding is that Pearce submitted an 80-odd man squad about a month ago, before cutting it to a 35 man squad about a fortnight ago. 6th July rings a bell for when the final, 18 man squad, has to submitted - and will therefore be announced - but don't quote me on that.
By all accounts, the FA have agreed with Pearce to back-track ever so slightly on their statement that no player who went to the Euro's will feature in the Olympics, as they both want Butland to play. And in fairness to the FA, when they made that statement, Butland was presumably not in line to go to the Euro's - he only got called in as Ruddy's replacement remember.
Sounds like the three over-23 players will be between Beckham, Giggs, Bellamy and Lampard.