Here are one or two links if you are interested in the business of writing, or thinking about sit-com.
Ken Levine, writer of many American sitcom hits, has a blog here.
I also recommend Rob Long's weekly podcast called Martini Shot, broadcast by KCRW. It's only 4-5 minutes long, but is an interesting window into the comedy writing world. You can find that here. He is also the author of this wonderful semi-autobiographical book published a few years ago called Conversations with My Agent. He has followed it up more recently with Set Up Joke, Set up Joke.
Rob Long writes very well about the Biz, as it were. And there are literally dozens of TV shows about sitcoms from the past. But there isn't much out there on the technical subject of comedy writing itself. One book I read when I was starting out was Writing Comedy by Ronald Wolfe, writer of the now unwatchable On the Buses. But the structural stuff and the way in which comedy works is all useful, even if you end up writing jokes that don't revolve around 'crumpet'.
If I stumble across other resources, I'll put them up here. In case you're interested. You may not be. You may just like Hut 33. In which case, let me reassure you that I'm doing my best to write Series 3 at the moment - and it should be out in the second half of 2009.