I'm new to the forums, so can't post URLs yet
But yes, a fastboot does exist for OSX, and probably for linux (I haven't looked for it yet).
I just did a blog post about host two days ago. Check out silverwraith dot com / blog for how to do this on OSX. I mostly followed Timmy's directions, but the fastboot-mac binary is linked there which you'll need.
As for adb, I had it installed already from the SDKs. I can send you the OSX binary for it if you need, and probably dig up the linux one and any supporting libraries it needs. The OSX adb binary is statically compiled so it doesn't need any supporting libraries. Perhaps the Linux ones is too