[HIJACKED!] What are the best OSS discussion group apps?

[Bart Silverstrim]

Duh!  It wouldn't be list-id because...well, it's the name of the 
mailing list, not the thread :-)

sorry, I had that header in mind because I had recently redone some of 
my filter rules and had to use list-id to...tada!...filter incoming mail 
to the right folders.

:-)

what is the mechanism used for sorting to proper threads?