It looks like when the vets and BG talked about doing workouts and keeping the team together during the lockout they weren't messing around. According to the article the summer league was the idea of BG, Mo, Foye. Not only is it great from the stand point of providing basketball for us fans to watch, but it also evidence of the strong chemistry this clippers team has. This is exciting stuff. The league is set to begin September 12th.
Edit: found a more detailed article, according to the article the teams would only be able to be 7 players (of course that could change), and the games may be streamed online.