Obama's support of the Keystone Pipeline isn't exactly a monumental change in policy, but rather, it's one part of his strategy to curb the conversation on rising gas prices--gas prices which are dragging down his approval ratings. Back in January, if you recall, Obama opposed and denied the Keystone Pipeline proposal--a plan to transport crude oil from Alberta Canada to refineries on the Gulf Coast. Opponents of the plan cited environmental concerns, while Republicans cited Obama's disregard for the creation of new jobs and attacked his policy in the criticisms they leveled on the president.
So why the change of heart if this same, if this is the same maybe-evil pipeline from January? Well for starters, it's the Southern portion of the pipleline, and as his Republican critics have said, it's mostly a political posturing opportunity since the process would've started without an Obama approval. BusinessWeek reported that Obama's approval isn't going to speed the process which would ultimately allow crude oil (which is currently in a bottleneck in Cushing) to flow to Texas' refineries--it won't be operational until 2013.
But Obama's brief speech (around 12 minutes) in Cushing today did allow him to explain his quasi walk-back--blaming it on timing, Congress members (though he didn't say it, we're guessing he means Republican Congress members) who "thought it might be a fun political issue" and his environmental concerns in Nebraska. And perhaps most importantly, it allowed him another chance to change the currently-damaging conversation about gas prices in America--it's been the focus of his current trip.