Ultimately, I think Homebrew will win out because:
(1) It is on github (http://redmonk.com/sogrady/2010/04/01/github/)
(2) The Homebrew DSL is far, far easier to work with than Gentoo ebuilds
(3) From what I've seen, you don't need root privs to develop Homebrew formula, but setting up fakeroot to develop Gentoo ebuilds is a pain.
Homebrew or not, VM'd Linux hosted under OSX is a sweet spot for what I'm working on.
Ultimately, I think Homebrew will win out because:
(1) It is on github (http://redmonk.com/sogrady/2010/04/01/github/)
(2) The Homebrew DSL is far, far easier to work with than Gentoo ebuilds
(3) From what I've seen, you don't need root privs to develop Homebrew formula, but setting up fakeroot to develop Gentoo ebuilds is a pain.
Homebrew or not, VM'd Linux hosted under OSX is a sweet spot for what I'm working on.