I don't have much scientific knowledge on the subject but I have found plyometrics (in various forms) to be quite helpful in my training, particularly for shorter events. Obviously as you have noted they are no replacement for aerobic conditioning but they are very helpful for developing quickness, speed, and power which are of great use in the sprints and middle distances. El G, Coe, the Ethiopians, Rodal, and Webb as well all did some form of plyometrics. They seem to help put a spring into your stride.
back in high school we used to do some light plyimetrics before each run, including skips, hops, bounds, and hurdle exercises (walking over hurdles).
In addition if you look at the sub 1:50 800m thread OldSub4 talked about how increasing his jumping ability through basketball training may have contributed to a significant drop in his 800 time