I have just released my Java3D FPS 'Arabian Flights' under the GPL, so if anyone wants to make an outdoor FPS with Java3D, you can use AF as a starting point or just for some reference material. its got a physics engine that detects collisions between particles and a landscape that tiles, so there's no edges. It also has simple buildings and basic smoke effects.
SourceForge project: http://sourceforge.net/projects/arabian/
oh, and here's some random screenshots:
(This is kind of a cross post with the "Your Games Here'"forum, but I think it's appropriate here too)