To update, go into Maps on your phone, tap on the menu icon, then 'Map Loader' and then 'Check for updates':
So only a 0.01 bump on the base map version number, but the 17.12.2012 release date is reassuring. Do let us know if a map error near your house has been fixed or if a particularly new road is now included. I checked with users in other countries and new map data is also available for them, so the update seems worldwide.
Checking for, and receiving the maps update, installed by default to mass memory or microSD, depending on which phone is being used. I tested the update on the 2012 Nokia 808 PureView and the 2009 Nokia X6, running S60 5th Edition and both worked fine (the latter via Nokia Suite), but I'd be interested to hear if the update is also shown as available for even older phones.