Thomas Van Der Wal compares LinkedIn and Facebook (with a bit of Twitter thrown in). Here’s the upshot:

Michael Arrington writes about Facebook has LinkedIn in their Crosshairs, but I have been finding Facebook becoming increasingly less valuable the more people I have connected in it. The converse is opposite for me, LinkedIn becomes incredibly more valuable the more people I have in it. The reason for my derived value is simplicity.

The whole post is really good.