Just don't forget the users who could care less about the community and just want a place to put save bookmarks. Google Bookmarks is good for this, but I like to categorize my bookmarks in bulk and Google does not work well for this.

Thats a given... I was wondering along the lines of technical features.

Well, you have to enable a community through the technical features, is the thing. The community has to be intrinsic in the tech.