The code works with Mozilla, Firebird, Safari, and all tested versions of IE. Performance is quite reasonable: around 60 HTTPS transactions per second between two 1GHz i686 machines running Linux on FastEthernet, according to the siege benchmarking program.
Also see the more portable CL-SSL bindings (using gray streams) by Jochen Schmidt, which are distributed as a component of the ACL-COMPAT library.
SSL-CMUCL is available under GNU LGPL from www.chez.com/emarsden/downloads.