Many a Nexus One owner has been eager to trawl through the forums in search of the recently released Froyo 2.2 update for the device. However, it has recently emerged that the update was only a release candidate (check out this article for more details). This is rather unsurprising when it is put into consideration that only the review phones seemed to get the OTA update, and also that the update itself has been rather buggy.
One of the major problems comes in attempting to download protected applications from the Market. It seems that the Market simply isn’t ready to be used by a device running Android 2.2. Therefore, it becomes necessary to roll back the device’s ‘fingerprint’ to fool the Market into giving you access.
XDA member Geniusdog254, has written a nice build.prop modification to do just that, without losing any of the Froyo goodness.
You can find more information in this thread._________