Is it true you cant use wireless tethering on 2.1?
A completely stock un-rooted phone can tether using PDAnet or similar (wired or bluetooth, wired requires a specific client)
A stock ROOTED phone (some would consider a rooted phone to no longer be "stock") can tether using barnacle for bluetooth or wifi tethering.
A rooted 2.1-based phone with a custom kernel can tether using android-wifi-tether for bluetooth or wifi tethering.
A rooted phone with one of a few specific custom roms can do wired tethering that does not require a specific client (RDIS).
Cool CM Tricks
custom_backup_list.txt - make a list of files in /system that will survive a nightly install (ringtones, notifications, system apps, wallpapers, whatever)
in Terminal Emulator, set this as your shell command: "/system/xbin/su -c /system/xbin/bash". You get all the features of bash, root access, and you can still use the initial command field for whatever you want (default is adding /data/local/bin to your path)