CyberGamer.org has been running an australian based league for some time now, but it's now setting it's sights on a US league that once up and running with a larger amount of teams, will be on a year round basis comprising of multiple seasons.
CyberGamer is already quite experienced with running leagues of this sort, already having over 82,000 registered members that play in CoD4/LoL and various console tournaments from all over Australia, have various sponsors that you can view on CyberGamer.org, and have good management making extensive use of public advertising including but not limited to Australian PC Gamer.
We've started our 5v5 League and have several teams ready to play, but we need more. The league is setup so that it's friendly to both hardcore and casual teams alike. We run a CGO system based on challenges. All of the information is on the website, as well as all of the rules and formalities.
The rules are located here: http://www.cybergamer.org/forums/thr...042/5v5-Rules/
You can create and register your team here: http://www.cybergamer.org/teams/pc/lol5v5/
If you have any questions, feel free to e-mail me at Nanten@HokutenGaming.com or post something in this thread, I'll try to answer as quickly as possible.