Marco Antoniotti's blog on Lisp and other interesting bits of programming.
CL-UNIFICATION bug fixing
Thanks to Masayuki Takagi, a not-so-obvious bug was fixed in the basic unification machinery of CL-UNIFICATION. This led to the addition of a couple of new utility functions and some other cleanups (hopefully).
The result should be in Quicklisp in the next round. Otherwise you can always clone/update/pull from the main repository.