As I mentioned a few weeks ago, Edwards in the televised ABC debate a month or so ago aligned himself with Obama as a fellow "agent of change", in opposition to Hillary who he described as part of the Washington 2-party establishment. So to me it would be unnatural for Edwards to at this stage endorse Hillary Clinton. That would be a pretty clear backroom deal, inconsistent with Edwards' previous rhetoric.
Endorsing Obama would be consistent with what Edwards said prior, even though that would apparently be a backroom deal as well.
Although, after seeing both Ted Kennedy and Caroline Kennedy give unprecedented endorsement to Barack Obama as the heir-apparent to JFK and Martin Luther King Jr., and having the people of Massachussetts still give the state's Democratic primary victory to Hillary Clinton over Obama, I don't know how much difference Edwards' endorsement would make, one way or the other.
