Hi Daniel,
I'm glad you found the
http://schemespheres.org project interesting. It's been used by four student teams to build little Android games with Gambit, and even though I couldn't work on it for the last 3 months, I plan to keep working on it. My intention is to make it easy to build real multiplatform applications by providing a compilation of selected modules (some I built, some are compatibly licensed by the community MIT, BSD or similar).
As soon as a simple and flexible module system is built for Gambit, it will be built using it (unfortunately Blackhole didn't make it easy to handle C files and cross-compilation, which has been long discussed here). At the moment, it uses a set of scripts for managing compilation and macro expansions is just a two-step process involving syntax-rules (through Alexpander) and then define-macro as natively supported by Gambit.
Many things to improve, and happy to bring collaborators in.
Cheers!