It is not very common for Apple to perform software updates on its simpler iPods, but this time it was the turn of the iPod with the most capacity in history, the Classic.
Now we can make Genius Mixes with their 160 GB of music that we can have at most, which personally seems to me a real brutality and barbarity, by the way. Device speed has also been improved and small bugs fixed.
You can update it yourself in iTunes, when you connect it, it will appear as available. Obviously it is highly recommended to do it.