Today Nikon released a firmware update for the Nikon D3100 DSLR camera. The update appears to fix a number of minor issues, none of which I noticed when testing the camera myself.
Link to US English Version of the firmware Update (Windows and Mac OSX)
When the update is compelete the firmware screen on your D3100 should look like this:
BTW took this snapshot with my iPhone 4, so the quality isn't the greatest.