I know the founders personally and definitely agree that it was one of the best (or at least most useful) YC startups. I don't know the whole motivation behind it, but I know that the founders decided to pursue other paths and to stop actively developing new features a while back but will keep the site running in it's current state. I still use the site to brainstorm whenever I start a new project.
I guess your observation is a bit late...their blog hasn't been updated since Dec 2006...and their frontpage content is the same since the last time I've visited it (and it's been long time since then).<p>I guess it's weird since enterprise collaboration software actually took off the past 2-3 years...They should somehow be part of that market...
Yeah it has a lot of potential! I wondered the same myself and posted on their forum asking....<p>Maybe the founders are focusing on other aspects of life - wife and kids maybe?