It's up on the file releases page now; enjoy.
from the NEWS file in the distribution:
changes in sbcl-0.8.21 (0.9alpha.1?) relative to sbcl-0.8.20:
* incompatible change: thread support for non-NPTL systems has
been removed - locking is buggy and unreliable. A threaded
SBCL build will now warn at startup and refuse to create
new threads, unless futex support is detected in the kernel
* incompatible change: the top level REPL now has only an ABORT
restart associated with it, not TOPLEVEL and ABORT as it used to.
TOP and TOPLEVEL are now available as debugger commands for
returning to the top level.
* incompatible change: forms evaluated in the REPL now use the
global optimization policy.
* incompatible change: user- and system-initialization files are
no longer processed with LOAD, but by READ and EVAL; hence the
global optimization policy, startup package, readtable, etc,
can be set by them.
* The .fasl file format number has been incremented because of
various incompatible changes.
* internal entry point details and argument counts no longer appear
in backtraces unless explicitly requested by setting
* built-in and standard functions no longer have names like "top
level local call to FOO".
* fixed bug 32: functions defined in non-null lexical environments
now have more legible printed representation
* fixed bug 33: functions defined in non-null lexical environemnts
are now more amenable to inspection by INSPECT.
* workaround for bug 354: XEPs no longer appear in backtraces unless
* fixed bug: receiving the signal which results from attempting to
write to mprotect()ed memory (SIGSEGV on Linux and some *BSDs,
SIGBUS on other *BSDs) on architectures where the C stack is also
the Lisp stack (x86 and x86-64) from foreign code no longer leads
to debugger confusion or wild instability. (reported by Cheuksan
* fixed bug: COUNT and EQUAL no longer issue compiler efficiency
notes when operating on objects known to be SIMPLE-BIT-VECTORs.
(reported by Lutz Euler)
* fixed bug: (TYPEP X '(MEMBER ...)) no longer returns a list in
compiled code. (reported by Paul Dietz)
* fixed bug 276b: mutating with MULTIPLE-VALUE-SETQ a binding of a
specialized parameter to a method to something that is not TYPEP
the specializer is now possible.
* fixed bug: the MAKE-INSTANCE optimization is now correct in the
face of package deletion.
* fixed bug: LOAD should bind *LOAD-PATHNAME* to the merged
pathname. (reported by David Tolpin on c.l.l)
* contrib improvement: the SB-SIMPLE-STREAMS contrib now defines
STRING-SIMPLE-STREAM and FILE-SIMPLE-STREAM as subclasses of
STRING-STREAM and FILE-STREAM, respectively.
* contrib improvement: SB-INTROSPECT handles more of SLIME's needs
than previously; in addition, its test suite is now run on build.
(thanks to Luke Gorrie)
* a more robust x86-64 disassembler. (thanks to Lutz Euler)
* optimization: added a immediate representation for single-floats
* fixed some bugs revealed by Paul Dietz' test suite:
** MISC.564: defined out-of-line version of %ATAN2 on x86.
** attempting to create a package with a colliding nickname causes
correctable errors to be signalled.
** MISC.572-574: :START1 and :START2 broken for simple-base-strings.
** several x86-64 backend bugs related to sign-extension of immediate
William Harold Newman <william.newman@...>
"in fasl file format version 53, but this version of SBCL uses format
version 54" -- sbcl-0.8.21 complaining about one of my projects