This is kinda cool as Google's aggregating sites that are themselves about aggregation. For a site with not too many network effects in play, I might be worried

This is kinda cool as Google's aggregating sites that are themselves about aggregation. For a site with not too many network effects in play, I might be worried. And since Google actually knows a lot about your network via Gmail, they might even have an edge over other sites that make you go through the pain of explicitly adding friends.