I have been toying with Virb for hours now. I would be completely okay with ALL of my friends moving from Facebook/Myspace. This web application is excellent, and seemingly progressive With facilitated page customization (as opposed to hacked Myspace pages and static Facebook profiles), Flickr integration, video/photo/music uploads, varying account types, AJAX backend, a group system, and iTunes logging; I don't know how other networks will be able to keep up. With that said it's not perfect...

While Virb has loads of awesome features, they have reinvented a few wheels. Last.fm does the iTunes tracking, and does it better. Why can't I just give Virb my Last.fm username and password? Last.fm has an elaborate API. While Virb allows users to include YouTube videos and Flickr photos Virb has still created their own service for these mediums... this may get confusing for the less internet savvy. Music accounts can add their own albums and tracks (something Facebook can't hold a candle to), but why not integrate with PureVolume, one of their other products?
If Virb stays open to incorporating other web services (like Twitter), it will be the end all be all as far as social networks go! I sure hope they don't sell out... *cough* MySpace *cough* Facebook *cough*

P.S. Tagging is the way to go!