May the best aggregator win!
FriendFeed may just very well already have a lock. FriendFeed is the site where you can track not just what your "friend" is doing on Facebook, but all of their online activity. Did they post to twitter, did they favorite on Delicious? Have they posted to YouTube? FriendFeed tracks it all in one place for you.
FF also offers the option to comment, which for bloggers has been of somewhat concern. Your blog post may appear in FF and could be commented on in FF and that comment will not be reflected in any way on your blog. An entire conversation about your organization's blog post, but not within your blog. Hmmm. Worth checking on, right?
FF is definitely the next level in social networking management.
Check it out.