On his Twitter feed, Meb Keflezighi has written, "I am thinking of challenging @usainbolt to a race. Location & Distance to be determined, money for charity. Usain, U interested?" Bolt has yet to publicly respond.
In such a race, the main thing to work out would be the distance--short enough that Bolt's speed still matters, long enough that Keflezighi isn't still on the start line when Bolt finishes.