Well, XP is about to be obsoleted. Enterbrain announced RPG Maker VX is coming out in December in Japan.
It's most notable features are easier mapping, eventing, and the implementation of vehicles *JOY!*.
Of course, as with XP there are things that seem to be left out of VX for no obvious reason. The battle system supports more cool effects, but has completley eliminated your characters appearing on the screen at all. The resoloution is smaller than XP at 544×416, which is just about the oddest resolution I've ever seen. The new charsets suck out loud, and the backgrounds are literally higher rez versions of the old tilesets from RM2k/RM2k3. Face sets are back though, and look really good.
All in all, there's a lot they're keeping under raps right now. I'm hoping there will be a few more features than advertised at the moment, such as maybe an alternate battle system or two packed with it, because the current battle system looks like it somehow sucks worse than the current one.