I've got a 21-inch iMac (newest budget version) with Snow Leopard running Win 7 in Bootcamp. Just wanted to make absolutely sure that I can install Lion on an external drive without messing up anything. Also, will a usb 2.0-drive be sufficient for running Lion, or is it necessary to have a firewire-drive for increased speed?
Yes you can, no problem. Here is a procedure for you to follow: http://www.makeuseof.com/tag/install-osx-lion-external-drive-test-mac/ Sounds like this developer is using USB, so you should be okay.
Thanks for the link Now I'm just hoping that an external HDD-cabinet with thunderbolt will hit the market