Yes, I know it can use a huge amount of battery. But I haven't been using it. I configured it (ie, put in my WPA key, the same one I had on my Nexus One) so I could use it, but then turned it off.
I shutdown my phone last night (took out SD card to copy a bunch of music over quickly). Since I turned the phone back on, I haven't even been into the wifi sharing menu and it's used 15% of the battery.
I will try removing the config and see if it crops up again in the list tomorrow.