Several gliders have reported that the LA Metro system is segway friendly (but I think this doesn't include buses). I don't have first hand experience, so I can't give you details like when you have to walk your segway. Santa Barbara buses only allows them if you are disabled, but an alternate commuter bus going from Santa Barbara halfway to LA allows segways. The main reason for the difference is that the commuter buses have underfloor storage bins.
Steven, segways are an incredible solution for the "first mile". Check out these link (
http://www.calstart.org/programs/cm/...php?p=programs ) and (
http://www.calstart.org/programs/cm/FM_Vol_2_No_1.pdf ) where they mention a half million dollar program (EasyConnect
http://www.easyconnect.com/ ) by the California DOT utilizing segways. The cool part about this program is that it's employer sponsored. Talk about cool perks..."yeah, my boss makes me ride the segway/train to work". I wish I had employers like this!