Okay, solar asked me yesterday, and I think this might be the good moment to 
start this out.
Right now the x86-fbsd keyword is not being used in the main tree, and the 
whole Gentoo/FreeBSD is handled in an overlay, sharing the ~x86 keyword with 
standard Gentoo/Linux.
Unfortunately this has a series of drawbacks:

- we need to package.mask packages that could just not have ~x86-fbsd keyword 
at all (because being linux specifics);
- we can see the last working version of a package go away because later 
versions are ~x86 and they don't work for us (old flex might have been an 
example but that's now fixed; findutils can be another example);
- we cannot make sure that the deptree is satisfied.

To bring ~x86-fbsd keywording in main tree, we mainly need to move a true 
profile in the tree, not a dummy one, mark it as indev and start the 
keywording. (I've already cleaned up the default-bsd/fbsd profile so that it 
does work with the current base/ profile.
As long as virtual/libc is not in the dependencies, it shouldn't trigger any 
kind of problems to leave the sys-freebsd category in the overlay, if we 
really need to start needing that, I'll see to make the ebuild quality level.

It's not going to be a quick thing, as I'm mostly alone with Gentoo/FreeBSD 
right now (help is always welcome), but times are mature so that I can 
provide a decent experience to users.

Can anybody name a showstopper to this?

-- 
Diego "Flameeyes" Pettenò - http://dev.gentoo.org/~flameeyes/
Gentoo/ALT lead, Gentoo/FreeBSD, Video, AMD64, Sound, PAM, KDE