The UDP support of LispWorks (lispworks-udp) can almost work! Now most of APIs are stable.
We have at least two customers: one is ourself, the SNMP package, the other is IRCAM, some people are porting OMax (http://www.ircam.fr/equipes/repmus/OMax) from MCL to LispWorks, which depends on lispworks-udp.
We should release the 1.0 version after several weeks. Hope more people use it to do UDP jobs on LispWorks, before LW can official support the UDP networking.