I have searched the forum to see if this had been posted (which it hasn't), so the Nokia update for the Next G 6120c is now available from the Nokia site. It is an application that you download and install on the computer and when you connect the phone and run the application, it checks via the internet the version required and proceeds to download the firmware. The first phone takes approximately 30-40 minutes (depends on internet connection speed) where the firmware is downloaded to the computer and then installed onto the phone. Every phone thereafter will take approximately 5 minutes.
It was released last Friday (18/01/2008) and we have been using for a week and so far after 30 odd phones everything looks good.
The only bug I have come accross so far is if you try to upgrade the phone when the battery is not fully charged (ie dropped one bar), the updater application will tell you to fully charge the phone and try again. If you plug a charger in and hit retry, the application will lock up on a particular screen and will go no further (even though a little blue/white horizontal barber pole type progress bar flashes). If you get this message, cancel the update and re-run the application when the phone is charged.
My suggestion is to fully charge the battery or have on charge while doing the upgrade. Also to check version of phone, type into the keypad *#0000#. Most phones will display V 3.70. This upgrade will update to V 4.21 which will fix bluetooth related car kit issues. The software can be downloaded from -> Nokia Software Updater
Note - this Software Updater does a whole swag of other Nokia phones as well.
Nice keep it up bro