If Wave brings all of their contacts and socializing into one central hub, its going to have some competition.

Mozilla is already working on Raindrop, which sounds like a pretty useful tool. There will be others. On the other hand, it could go the Twitter route, where people will struggle to get it for a long time, and slowly start finding uses that suit them. That ahha moment hasnt come for everybody thats used Twitter yet either, but theres no denying that service has made its mark on popular culture.