So today I decided that we probably ought to move forward rather than be stuck through forces beyond our control, so I kludged around the GC problems. SBCL CVS HEAD should now be roughly well-behaved, and certainly shouldn't be so laughably fragile as it has been for the last week.
This will unblock some of my current work, such as improving the performance of SBCL on various benchmarks, and a better interface for compile-time customization of diagnostic messages. I hope it also unblocks other people's stuff, but it's been quiet (though not silent, fortunately) recently.
There are a couple of other things I feel I should comment on. Firstly, Edi Weitz has ported ASDF-INSTALL (briefly: a lisp tool for downloading "third-party" libraries) to a bunch of other (i.e. not SBCL) Lisps. As a lisp programmer, this has to be a good thing, because it means the constant whiners about lisp being hard get one more rebuttal... of course, I'm slightly disappointed that one of SBCL's killer advantages is no longer so clear.
The other thing is the notion that there is no "good" free Lisp (by which here I mean Common Lisp). I'm not sure, but I think perceptions are skewed, maybe by something like the Moon on a Stick phenomenon: people seem to accept problems in software they've paid for much more readily than in things they haven't — or, rather, I think they make an implicit calculation based on cost of the value of incremental improvements.
Maybe I should just sell SBCL for $200 a throw, or somesuch. It would be nice, if buyers could be found...