With the arrival of Lion, you might be stuck with a recovery USB drive that came with your Snow Leopard pre-installed Macbook Air. Seeing as these are slick little gadgets, it might be nice to use them for other purposes. After all, it's an 8 Gb flash drive just sitting there. Here's how.
Firstly one needs to remove the lock used by Apple. To do this, download sm32xtest (no need to look, Google has already found it) and open in Windows, for example through Boot Camp or on another PC. When you plug in the flash drive it will appear in the first line of the program. Hit 'start' and wait for the program to flash a big green OK.
Now you're ready to use Disk Utility. In Disk Utility, you'll see the flash drive mounted as 8.02Gb, so erase it and re-partition to your liking.
Thanks to many other posters on other fora; I found this, I didn't invent it.
[crarko adds: Try this at your own risk, although I suppose there isn't much to lose by it. Exercise whatever usual cautions you have in running Windows software.]
Mac OS X Hints