Drakon has posted a release for devs:
Hi.
Here is very good 2d physics library Box2D - http://drakon.xxl-web.pl/box2d/Box2D.rar .
Original site : http://www.box2d.org/
This is newest version from svn(rev. 205), optimized for PSP(it's uses VFPU for math).
Package also contains TestBed source and compiled demo.