If I recall correctly, Google Reader used to have the "and ## others liked this" string as a clickable object to list out all of the people who liked a post. If that's not feasible (due to the possibility of loading 1000 names), maybe allow one click to load up to some acceptable number of names, and subtract that number from the "undisplayed likes" count.

Mainly, I just want to be able to see the people who liked a post that are either following me or that I'm following.