New iPod: 5G.
Some sites on the 'net have started calling the new iPod the iPod 6G. But if you look at the changes (most of which also come with an update to 5G iPods) and compare those to what was changed between the original 4G iPod and the 4G iPod photo, it becomes clear that the iPod introduced today is simply a better iPod 5G, and certainly not a "new generation" of iPods.
Of course this is totally different for the other iPod lines. The nano is now at 2G - and so is the shuffle.
The 6G iPod is still forthcoming - and is actually expected to be released in January at MWSF. You know: The one with the screen which'll fill the entire face of the iPod.