I really enjoyed that site. I've only posted on it once, but I enjoyed seeing other people's posts and appreciated reading about entrepreneurial dilemmas.
The Startups Stack Exchange site didn't make it; the community required to sustain it beyond Beta never materialized.
See the Area51 proposal, where you can download an archive of the site as well.
Apparently it was resurrected as Bright Journey. I just got an email about this.
It didn't have enough ongoing activity, so it was closed down. It seems there were only a very small handful of regulars who were maintaining the site.
There are more details on the Startup Business site proposal on Area 51.
(Note that there is also a new proposal to try and get a new community of users around the topic.)