"I remember we were working with some rappers once and one of their computery professor types was processing all the singing and it came out really weird...perhaps he was using this sort of thing? Can anyone elucidate?"

Greg, from what I've been reading there has been criticism concerning the all pervading presence of auto-tune effects being used by Hip-Hop artists, to the extent that rapper Jay-Z condemned the trend (which some have felt was killing hip-hop) in his track D.O.A. or 'Death of Autotune' ("You rappers singin too much, Get back to rap you T-Pain'n too much"). In other words I imagine your intuition was probably correct and your rapping computery prof. collaborator was probably using auto-tune.