fyi, I've uploaded my gdb-guile branch to github.
It's in branch gdb-guile.
It's still very preliminary, and there are some open issues.
If you're interested take a look.
We'll have to see how things end up if/after it passes code review, so while I welcome all the help I can get, I'd feel bad if people write too much now only having to redo it.
OTOH, if you have as much fun with this stuff as I do, go for it. :-)
I'll be submitting snippets for review over the coming weeks.