The Dungeons and Dragons 4th Edition is coming (the core rulebooks will be out May-July 2008), and the
D&D 4th ed Preview Books are out already.
I really like everything that I've heard about it so far -- the fleshing out of standard player races, the centering of character classes and monsters around roles, the expanding of the 'sweet spot' (currently D&D is fun and playable at around levels 4-15, but lower or higher than that becomes less fun), the expanding of combat options for non-spellcaster classes, and so on.
I have a feeling I'll like it much more than the current 3rd edition (although I'll always have a soft spot for AD&D 2nd ed).
I haven't run a D&D game for a long time, nor really played in one (although I am currently enjoying the hell out of our [Hero 5th ed]-based Planescape campaign run by
theferrett).
But this is really promising.