I have created a funtoo for the Beagleboard X15. I can boot it and will be adding to it. The basic without xorg with full internet support boots in about 3.4 seconds.
I use the u-boot and Linux kernel from the latest TI SDK release. I use it on a Rev A2 board but it will also work on a Rev B1 board.
Funtoo is a source based Linux distribution similar to gentoo. So far I am not aware of any Gentoo or Funtoo support for this board. I plan to add support for the Beaglebone boards but that will come later.
If anyone is interested to work with me on this let me know.