In a recent Joystiq interview with Ross Erickson (Xbox LIVE Arcade's worldwide games portfolio manager), it was revealed that it is Microsoft's intent to release a game a week on Xbox LIVE Arcade. 

Peter Moore said there was going to be 160 games on the console by the holidays. Unless there's some huge amount of 360 titles we don't know about, a lot of those games are going to be Arcade games. You've announced 21-30 games by the fall. Do you think you're going to be able to hit the once a week until the end of the year.

It's a daily issue for us to continue working with the developers as they move towards their final milestones. We certainly have enough games in the pipeline – more than enough, in fact – to achieve that goal on a weekly basis. We're not announcing anything in terms of what's beyond Pac-Man at this point; there are enough games in the pipeline to last for a very, very long time.

Publishers typically shy away from releasing during the summer months, particularly with AAA titles.  The Xbox LIVE Arcade Wednesday release schedule has certainly helped alleviate the summer drought for the kids that play inside...

Full interview:  Joystiq