I have a Ubuntu 12.04 install on an external HDD. On my Dell Laptop, I tried to boot into 12.04 by connecting the USB 3.0 compatible external HDD to USB 3.0 port but it wouldn’t show the grub (v2.00-7ubuntu11) boot screen. A rather silly workaround helped, however. I connected it first to a USB 2.0 port so that the grub screen loaded. Then, I disconnected the HDD and reconnected it to USB 3.0 port and voila. I don’t know if it’s the BIOS or grub (or both?) but this is what I’m going to do from now on.
Fedora 16 Alpha is coming out soon and they have selected Fedora 16 wallpaper. Here is how I installed it in Fedora 15: