A friend of mine is using his free time to teach about Linux and FLOSS at a school - he managed to convince the school to do this on Saturdays.
Recently he did an interesting experiment with the kids: got bootable images for a number of distros and they put those on LiveUSB media and tried to boot and play with them. Unexpectedly, only Ubuntu worked and everything else failed to start, including Fedora 12 Beta, so their conclusion was "the school computer only support Ubuntu".
I was shocked to learn this, I had terrible pains with F11, which failed for every install I tried due to the Anaconda storage rewrite, but in my experience F12 was rock solid from this point of view.
But soon I identified what I believe to be the root of the problem, they used UNetbootin to write the live USB media, a tool which is supposed to work with a large very number of distros. I have no idea if Fedora 12 failed to boot because the media was written with a tool not updated for our new hybrid images or due to general suckiness of the tool, but I was really amused to read on UNetbootin web page (emphasis mine):
"Requirements: Microsoft Windows 2000/XP/Vista/7, or Linux. If you are having trouble with the Linux version, try the Windows version, it usually works better."Hint for my friend Tibi: next time use
"dd"on Linux. It will work better (at least for Fedora).