Some exciting features planned! I too am looking to make use of bullet and I've got some ideas for an abstraction of their C++ API - if you fancy it one of the days perhaps we can brainstorm a design for our mutual use?

Also if it's ok with you I'd like to support Castle scene files in my editor - your engine is more complete and advanced than my own and I thought it would be wise to compliment your work rather than reinvent the wheel