Editorial on Grist.com:
http://gristmill.grist.org/story/2008/2/4/23617/54464?source=weekly
Also has Obama & Clinton's green agendas...
Based on the writer, it comes down to these questions:
"Who will be more effective at getting a green agenda past the many obstacles it faces?
Who will do more to help downticket races and usher more Democrats into Congress?
There's been a lot of chatter about "theories of change" this election, but if you ask me, personal style matters a hell of a lot less than the number of reliable votes in Congress. So who'll get more downticket Dems elected? I think, as his recent endorsement by a string of red-state Dems attests, Obama will. He's got broader appeal with the Independents and wavering Republicans that will make the difference in close Congressional races.
So in the end, if I was forced at gunpoint to pick the greener Dem this election, it would be Obama, but only based on second-order effects, and only barely. By far the larger story this season is that both Democratic choices are advancing a green agenda substantially more ambitious than what was proposed by Kerry, Gore, or Clinton. It's hard for green Democrats to go wrong this year."