unrevoked is back... here's my write up as i remember doing unrevoked2 (doesnt say if it will work w/ post OTA phones)
http://unrevoked.com/recovery/
go there using your phone. d'l the exe file.
run the exe which should install a 'reflash.exe' program and a hboot driver webpage and some other files (.dll)
open the htboot driver
webpage and follow the instructions.
after thats done you should be able to connect your phone to computer. turn usb debugging on and read as disk drive.
then click the "reflash.exe" and it should do its thing