Discussion Questions: Whatever Happened to Forums?

Perhaps it's just me, but it seemed that a few years ago, more websites had forums for their users to discuss the site. At least internally, it seems like forums have been replaced by the corporate blog where users can comment on the posts...

Is there some reason that forums on corporate sites have become obsolete? Why wouldn't you want a forum on your site?

It seems like forums have been outsourced to Twitter, Get Satisfaction, et al....

Gabe