This Hill story has some details on John Edwards's potential strategy for a brokered Democratic convention. Edwards advisers say he'll have enough delegates to be meaningful:

Prince told reporters in a conference call that in “a worst-case scenario” Edwards would control 20 to 25 percent of the Democratic delegates heading into the convention. He predicted that Sens. Barack Obama (Ill.) and Hillary Rodham Clinton (N.Y.) would each have 35 to 40 percent of the delegates, well short of half the 4,049 needed to win the nomination.

The race could leave Obama and Clinton with nearly the same number of delegates because complex rules would divide delegates evenly among candidates who win more than 30 percent in the congressional districts that make up each state.

And there's a wrinkle for Democratic delegate rules--they're not necessarily bound to any candidate:

At the Democratic convention this August, delegates will be allowed to vote freely even if they are already pledged to a candidate, Wayne explained. But he expected that Edwards’s delegates would do his bidding.

Wayne said that Edwards’s delegates have been “hand-picked” because of their loyalty.
“That loyalty would probably extend to the convention, though Democrats have a rule that would not impose loyalty,” he explained.

Most experts predict that a brokered convention isn't very likely. But, after New Hampshire, the pundit class is increasingly embracing the slogan "Anything could happen."