This sort of info aggregation/overload will never catch on outside of the early adopter community. It's very value is predicated on having too much data online.

FriendFeed = the sociable guy/girl who mingles among all the groups at a party, bridging* people together

Facebook = the alpha/host of the largest and/or more popular groups at the party

* - http://en.wikipedia.org/wiki/Social_capital

Friend feed and other aggregators are all gonna have that potential by their very nature.

I wrote a rather lengthy comment about this some time ago:

http://news.ycombinator.com/item?id=123975