Alright. Erin Catto's Box2D (www.box2d.org) is going to be /the/ 2D physics system, as the success of his original Box2D has already created many spin-offs.
I want to be able to have access to the most advanced 2D physics I can have in ArcLib, but keeping the physics system up-to-date with Erin's new stuff is going to prove a challenge, and in order to accept this challenge, I started a seperate box2d4d project on dsource which aims a providing a close-to-source as possible translation of Box2D.
The ArcLib physics system upgrades is now a three step process, now without pressure of us ArcLib developer's having to develop new physics features ourselves, but merely staying up-to-date.
The pipeline goes like...
Erin Catto Updates Box2d --> box2d4d updated --> arclib updated if needed to support latest version.
Simple, mechanical 3 step process. The first pass will be the hardest, the rest will be easy and I can concentrate on other aspects of ArcLib, like lighting and the API. Until then, my time will be spent on box2d4d.