They are not account sharing and have the blessing of their realm's GM, for those of you who are worried about them going against the ToS.
Child's Play is the charity that the guys at Penny Arcade put together to provide toys, games, books and cash to sick kids in children's hospitals. The WoWathon team's goal is to reach $5000 in fundrasing for the charity and are currently near $2300. If you wish to donate to help them reach their goal, please go to their website and click on the Chipin button.
We are talking to them now, so stay tuned to WoW.com for an interview with the team.
[Thank you to the many readers who have tipped us about this awesome event.]