So I just joined Orkut (or actually I did last night when Andrew gave me the scoop), the new Google-spawned social network service (thank god the name doesn't end in "-ster"). I have to say that I've never used Friendster before, so I'm pretty impressed by the functionality of the service. It's really clean and useable. Much more so, I think, than LinkedIn, which has a clean layout, but a confusing interface to find contacts. Orkut really seems to make it easy to see info about my links, and see the contacts of others as well. Maybe this is old news to you social networking gurus out there, but to me it's pretty neat.
Orkut's server seems to be holding up very well (especially for a site using Active Server Pages) and it's definitely reaching a critical mass - I can refresh the page and literally watch the Blogger group grow in real time.
I have to say, even 8 years after HotMail is launched, I'm still amazed at the ability of viral sites to grow...