I would love to see the "why" in a blog post.

When I first heard the launch of this product I was a bit skeptic. 37 Signals sells good to techies (and where techies are in charge of the order) but this particular product was specially geared towards non-techies, hence it would be really hard to make it work.

My guess would be that the system didn't organically acquired enough users, I might be wrong, and they simply cut their loses. Maybe they'll post something in the upcoming days to enlighten us.

Considering they constantly and harshly criticizing everyone else's business model and they literally wrote a book on how to run a business like this, a blog post with details is expected of them.