No. I've had a wavesandbox.com account since late May or early June. Yesterday in my wavesandbox.com account there was a Wave with a one-time-use link to create a normal Wave account.

These normal wave accounts (@gmail.com) are what everyone is getting now, and are totally separate from the previous @wavesandbox.com accounts. (Yes, one day, probably every Gmail account will be a Wave account - but not for a while).