My wife has an HTC Hero, which is slow and will not get OEM upgrades beyond Android 2.1. So we put CyanogenMod 6.1 on it, so now she has Android 2.2 and various settings that allow the phone to run faster. (Well, mostly kill pigs faster.) I'm pleased that CM7 will also support this old phone.
I have an Evo already running HTC's flavor of Android 2.2, and have held off on moving to CyanogenMod because until recently it didn't support the Evo's 4G (Wimax) data feature. That's now in CM7 though. The more I see of CM the more I like it (and the less I like HTC's Sense interface), so I'm eagerly awaiting the final release of CM7.