John Battelle is reviewing a bunch of predictions that he had for this year, 6 months in. Lots of good technology, state-of-the-web, and so on items. I'm picking out #7:
7. Second generation blog/RSS aggregation sites will come close to combining directory functions with LinkedIn- and recommendation-engine-like features - think Amazon+Yahoo for the blogosphere....
UPDATE: Not yet, unless I've missed something.Battelle Media: A Year Of Predictions, Six Months In
I don't think we're quite there yet in terms of standards/formats/interfaces to enable this. But Drupal has a lot of these pieces baked in.