NewsVine, reddit, digg, memeorandum, TailRank, News Alloy, CommonTimes, not to mention old greybeards Slashdot and Plastic. Is there really that much demand for socially customized news out there?
More importantly, are there enough ad dollars to support them all? I think I'm with Steve Rubel on this one, shakeout approaching.
A particular theme I'm waiting to see play out is responses to The Tyranny of the Crowd. As far as I know, all of these sites work for one large to vast set of participants.
I still haven't figured out why no one has gone meta and let users define and manage smaller communities with their own sets of sources and restrict the algorithms to those smaller groups. This would probably make the personalization algorithms more viable, at the cost of not having enough participant data, and having to come up with decent designs for managing social boundaries. Talk about targeted ad buys though!!