I'm currently dual-booting OSX and Ubuntu on my Macbook Air, but it'd be nice to run OSX within Ubuntu via VirtualBox. This seems possible using VirtualBox and is legal - there's even a post on an Oracle blog describing this: http://blogs.oracle.com/karim/entry/installing_mac_os_x_in. Actually, I've read elsewhere that it's only legal with OSX Server, but can't find a reason why it'd be illegal with normal OSX - please let me know if you think otherwise.
The problem I have is that a MacBook Air doesn't come with a bootable DVD, but with a "Reinstall Drive" which is a USB stick that comes up as a CDROM drive. It doesn't seem to be ISO9660-formatted though but has an Apple partition table, with OSX installed on an HFS partition. refit says that it has a "boot.efi" as well. I don't know Apple booting/partitioning very well and would really appreciate some advice on how to convert this USB into an ISO or boot it in VirtualBox some other way.