From a programming standpoint Getting the info from yahoo calendar would be easy (via several different methods). I don't know what file format gpe-celndar uses. is the format documented (I assume it is, but a quick google didn't return anything)? if it is, then it would be fairly easy to do. (1/2 days work?) and another 1/2 day if you want to be able to synch seemlessly in both directions.

So yes, it could work. But, Having said that, I don't use gpe-calendar.Hopefuly someone who has a need for it, and the programing skills will pick it up.

-Jason