I think data refers to the data sync setting which, when disabled, prevents apps from connecting to the internet. But, on 2.2 you have more options, and when you pick one that disables data sync, it specifically says "During this time the phone will not sync any data.", which contributes more to it being the data connection (things like AppBrain, Gmail, and other apps that sync every so often), which would be strictly wifi/3g. GPS and bluetooth are not part of the data connection so they would not be disabled during that time.
I could be wrong as I have my phone set to performance and never messed around with the settings much, but that is my understanding of it.
EDIT: Also, it doesn't really disable 3g, it just prevents apps from using it to transmit data. You will still receive calls and other things that take place over 3g if your phone has the data sync disabled.