Tuning inaccuracies become a problem when the music incorporates several key changes, as in jazz or classical, or when a lot of gain and distortion is applied, as in metal. There are a lot of different 'solutions' out there, ranging from nut modifications (such as Earvana), to weird fret shapes (Yamaha wavefront), both of which which preclude the use of a capo. Unless someone figures out how to time-travel, and slaps Pythagorus upside the head :D , we're pretty much stuck with choosing a compromise we can live with.

[u]Update[/u]: Check out this thread.

[Edited by Lordathestrings on 07-27-2002 at 03:35 PM]