+1. will be going from cyan to stock again when froyo comes out. but how?
Just out of interest (I am not making any judgements), why do you want to go from CM to stock as opposed to a CM modded version of 2.2?
Or are you just assuming 2.2 will drop before CM has time to mod it so want to get on it asap?
You will have to wait until either someone posts a stock 2.2 ROM that world with rooted phones or someone like cyanogen updates.
Once a different recovery is installed on the phone, the OTA system will never work again. Not even if you go back to stock.