*Note - just in case you're confused, "Coed" refers to a group that accepts all sexes.
BiPgh's listserve (Coed)
Bisexual Women in Pittsburgh - women only, obviously
Bi-girl-pride
BiForum (Coed)
the-b (Coed)
BiNetUSA Group (Coed)
Pittsburgh Bi and Lesbian Women
Soc.bi (Coed)
BiGi - for bisexual men
Bi-Men-Pittsburgh - for men and bi couples, according to their description
WomBAT - for bisexual women
Bisexual Community and Support - okay, so it's a message board, not a listserve. Still good.
Spouse Support Mailing List - for straight folks with BGLT spouses
BiParents list (coed)
South Hills GLBT
Gradykes - queer graduate students in the Pittsburgh area
PghBGLTPagans