I just removed the OS X partition on a 2011 MacBook Air, leaving only the BOOTCAMP partition. For what it's worth, I then rebooted into Windows 7 normally without problem.
The partition map now looks like:
[ 1 (200MB) ][ 2 (17GB) ][ 3 (40GB) ]
1: GPT boot-thingie partition
2: Empty space, where the OS X partition used to be
3: The "BOOTCAMP" Windows 7 partition
However, I did not trust regular Windows tools to delete the HFS+ boot partition for OS X. It might have worked, but instead I booted from an OS X 10.8 USB key, and then switch into Disk Utility and remove the OS X partition using the GUI.
(Yeah, this is on an old "64GB" MacBook Air... which definitely is not big enough to dual-boot unless you have very specific, limited needs.)