Has anybody here actually been involved in purchasing this product? What use case did it solve for you?
I had a small team that needed to share documents related to a consulting project. Everybody needed to use MS products, access it from the web, be able to check-in/check-out files, have a common calendar, a team blog, and a quick wiki for client-related information.
Sharepoint did all of that, in an integrated fashion, right out of the box. We got it hosted for about 30 bucks a month.
In addition, everything is an RSS feed. So as people change things on a thread you're watching, you can catch it right in your RSS reader.
If you have a few offices or remote users it is really useful. Probably not even worth considering for less than 15 people and only if you have some existing infrastructure. For smaller teams a hosted solution or some of the other products mentioned might be a better fit. (123together.com and intermedia both are OK for hosted SharePoint/exchange etc) Also, the blog and wiki stuff is still sub-par but the check-in check out stuff for documents does work pretty well.
I hate to come off like a fanboy, but I understand what Microsoft is trying to do with SharePoint and it makes sense to me.
I had another team that was just 2 or 3 guys working on a startup. We used basecamp and were very happy with it.
It depends on what you want and what your skill level is. If you're highly distributed and do a lot with Microsoft documents, then MOSS is a logical choice (and not extremely expensive). If you're just a couple of guys kicking around some code? Hack something together or use one of the simpler tools available on the web.
I'd draw the line somewhere around 4 or 5 guys, not 15 -- if you're doing something that's document-heavy. If it's just programming? I wouldn't consider it until I reached the 8-10 person team size, at least.