virtualbox.org

Would it be possible to install the Linux version on Mac OS X or would this be a bad idea? I figured it would theoretically work, and provide access to the 1_4_0 features but just without the fancy OS X gui. Thoughts?

Won't work. The Beta 1 for OS X has pretty much all features of 1.4.0 as it is based on a pre-release build of 1.4.0. There will be Beta 2 soon which will be based on 1.4.1.