As much as I would love it, no. I've been hunting this for a while myself. The G1 doesn't have Android drivers capable of monitor mode.
There is hope though. SHR Linux is a distro designed for phones. It started as an OS for the Openmoko Neo Freerunner and was planned to spread to more but it sucks on everything but the Freerunner and the G1.
Anyway, SHR Linux uses the wl12xx driver, a mac80211-based driver for the wl1251 (the G1's wifi chip). Driver stability is sketchy but if we're lucky it'll go into monitor mode without crashing. The procedure to use the driver is written here: http://www.htc-linux.org/wiki/index....am#Core_Status
I haven't tried SHR Linux yet, it's on my list of stuff to do. I think I'll give a go today.
Before someone says "the chip doesn't support monitor mode", yes it does. Some guy made monitor+injection drivers for the N900 which uses the same wifi chip as the G1. Google "N900 bleeding edge wifi" if you want to see it, it's on his blog. 'Why can't we use this working driver for SHR/Debian/Android' you ask? Because that driver was designed for the Power Kernel mod of Maemo, but the driver would definitely help devs if they sought to get monitor mode from Android.