Facebook patent on news feeds

This is a bit like the Blackboard patent on online learning:

"Facebook this week was awarded a patent pertaining to streaming "feed" technology, more specifically "dynamically providing a news feed about a user of a social network," complementing another patent filing that has been published but not yet approved.
The implications for this, as AllFacebook.com pointed out earlier on Thursday, are far-flung: Facebook may choose to pursue action against other social-media sites that potentially violate this patent. Twitter, as AllFacebook points out, is effectively one giant news feed, to the extent that it clearly has influenced some of the changes that Facebook made to its own feed technology."

How can we claim to encourage innovation with patents when this kind of thing gets through?

Update: Andres Guadamuz has taken the trouble to go through the patent and confirms it should not have been granted.