My friend and I are sharing MLB.tv accounts right now on our PS3's. It's really awesome, except for being blacked out from like 4 or 5 teams, including the Sox. Until I find a good proxy for use, I will just have to find random streaming sources to watch the Sox game, and then once the game is archived on mlb.tv, I can go back and watch certain innings or plays.
But right now I got the Yankees/Tigers game going, and will have the A's/M's game as soon as it starts.