Google opened sources code to their partners, manufacturers and everyone else and has made public the final Froyo update to Nexus One users. Though it has nothing to do with the iPhone launch, Froyo has been officially available to Nexus One as Android 2.2 version.
With this, it is now possible to manually download the update. And if you are not sure as to what you are dealing with, you just have to wait for the OTA update.
Chances are that all the users may not be able to take benefit of it at the same time, as rolling out updates is a bit slow process that varies by location too.
Well by opening the source to their partners, manufacturers and the rest, it is likely that they can start working on Froyo firmwares for the non-Google phones as well.
To check for updates:
Go to Settings -> About phone -> System updates.