[randomdata]

I participate in a few Basecamp projects operated by clients and from my point of view, it just forum software (like phpBB, IPB, etc.) with, arguably, a better interface.

I personally don't think it is that great, with many pain points that I encounter - which, I will concede, may be a case of using the wrong tool for the job over any shortcomings in the product itself - but it is better over having no group messaging system at all if you are working with multiple people at a distance.