But due to recent work, as of ABCL trunk r13538 we've restored this capability, once again making ABCL capable of bootstrapping an SBCL build. This may prove handy for individuals who wish to port SBCL to new platforms where there is a JVM available.
When we mentioned this on #lisp, we were asked how long it takes ABCL to build SBCL vs. SBCL building itself.
ABCL building SBCL
//build started: Thu Aug 25 15:12:30 CEST 2011
//build finished: Thu Aug 25 16:49:30 CEST 2011
SBCL building SBCL
//build started: Thu Aug 25 16:51:34 CEST 2011
//build finished: Thu Aug 25 17:07:47 CEST 2011
So, ABCL is roughly a factor of six slower building SBCL than SBCL itself.