I was wondering about this functionality as well. Sure would be cool.
I have never heard of a frontend doing this. Considering each game has a different format for its high score file, each game would have to be handled seperately.
I'm running MALA, and I noticed that when I'm in the game selection screen, if I hit player 1 button #2 (can't remember which key this is mapped to), a high score screen pops up but it never contains any information. Anybody have any idea what that is for?