I guess the best summary would be that Mike and Jerry, or Gabe and Tycho, started a web comic Called Penny Arcade in 1998. They have all of their comics posted on their site but much like RT they've expanded beyond just comics to doing web series and many other things, as well as being the proprietors of the Child's Play Charity. The community for said comic took off, and eventually they made a convention called Penny Arcade Expo or PAX. PAX got to be so big that it drew in all kinds of sponsors, game development companies and other nerdy kind of companies, and then became too big for itself. 3 years ago they split PAX up into PAX Prime, the original event still held in Seattle, and PAX East, the bigger event that resides in Boston. If you're a fan of comics, theirs is usually pretty funny, and if you're not, their community is good enough to make you want to stick around anyway. The conventions are always fun even if you don't know anything about Penny Arcade, and Mike and Jerry are both really funny and awesome people. That's the long and the short of it though, so go check out their site!
You're welcome! Personally, I didn't care much beyond their comics until I went to PAX East 2011. If you haven't been to a PAX, I URGE you to go. It's probably some of the most fun I've had in my life =]
The best guess is to watch Penny Arcade on Twitter, or visit their site daily. That's what we did to snag our PAX East tickets. You'll want to get them early however, because they sell out REALLY quick.