For my school, not only is it not frowned upon, but they wireless set up in every building that has a class room or lecture hall. Only portables that are temporary class facilities don't have 100% wireless, and even then you might still get a signal.
It is up to the individual professors of course what goes on in the class. One of prof's asked a couple students on laptops to email her their notes and she'd knock off a quiz for them or something so that she can guage the class (based on how they took notes). Another prof told us we couldn't have laptops at all.
I stopped taking my laptop since 1) it broke (which was a major damper to it's usefulness) and 2) I just played Nintendo roms on it any way
