The biggest issue is how mainstream they will be able to become. Many of my friends don't even know what the RSS is, not to mention aggregating them. ;-)

But I agree about the Search feature being the most useful part. I have found that search on twitter and FF conversations is pretty useful already and I use it often when basic googling is not enough.

Does the company generate profit, or even income?

I wish I had a billion dollars. I would spend them all to buy FriendFeed. Yep.