HootSuite lets a multi-person social media team manage tweets in a web based app that doesnt need to be downloaded (I'm a user). This can actually be a real business, unlike, oh, 90% of the twitter apps out there. Just because most of them are toys doesnt mean they all are.
HootSuite is one of only 3 listed that I'd heard of (HootSuite, FreshBooks, NowPublic), and I'd heard of it in a business context where people would pay -- a technical team at a Major Company sharing responsibility for a support Twitter account. So the dismissiveness is unwarranted.
I'm not sure, I don't really follow web 2.0 stuff. The list does seem a bit West-coast biased though. I can think of other Canadian tech and software companies (Idée, for example) that are more interesting to me than HootSuite, but it's not my list.