I have installed windows xp/vista through bootcamp with snow leopard (boot camp 3.x) several times. After a fresh installation of lion on my macbook air, something has changed.
With boot camp 4.0, I cannot create a bootcamp partition for windows 7 without external cd-rom, which would not occur with snow leopard. I tried to use usb stick and virtual windows 7 cd on the usb stick however, both not work.