Google doesn't necessarily need to conquer social, but they definitely need to understand it better. They wasted a lot on wave and pissed a lot of people off with buzz. Plus the way the gchat contact list and the greader following work is completely mysterious, and that's kind of an important aspect of their social backbone.
Buzz and Wave both still have potential though. For me, if they would just roll out a standalone Buzz site that lets me view Buzz's and post without going into my GMail inbox, I'd use it a lot more. But having to go through GMail just feels incredibly clunk.
Wave also has tons of potential, but they need to do a better job of explaining to people what it's useful for.
And as somebody else pointed out, a better UI would be nice as well. Using Wave is still confusing to people who are used to different metaphors.
