The app shows your IMEI and generates the NCK code, but it doesn't attempt to apply it, so you have to note it down and follow the normal routine of inserting a different SIM into a ROM that cares about these things. See here for more details, and a video from Paul! (Maybe the next version will be able to automate this a bit, but don't hold your breath.)
The "Reset Attempts (and Lock)" button will reset the phone's internal idea of how many unlock attempts you have back to the initial 5. It will also put it back in the state where it will prompt for the NCK code when you use a different provider's SIM. This may be useful for putting the phone back to (seemingly) the factory state, or for the reported occasions where interactions with Orange [unblocking a phone?] have reset their end of the network lock [?not sure about this?].
HAPPY CHRISTMAS ONE AND ALL!!
Edited by Arr Too, 28 December 2010 - 01:22 PM.