It is a temporary "solution" until sbcl 0.9.2 and the thread object based interface.
The changed interface is in the sbcl cvs with many bug fixes. 0.9.2 has several deadlock possibilities and is not recommended for serious use. On the bright side threads on x86-64 are supported.
2005-07-01 Gabor Melis mega@hotpop.com
* swank-sbcl.lisp (threaded stuff): make SBCL 0.9.2.9+ work while retaining support for 0.9.2
The thread id mapping code is messy and can potentially exceed 2^27-1 leading to communication problems with emacs.
Gábor