Full disk encryption for Mac OS X is on the roadmap for 2nd half of 2009. We currently offer a vDisk solution for OS X that is somewhat similar to the built-in FileVault feature, except ours is more flexible and centrally managed.
Full disk encryption for Linux is listed on the roadmap for first half 2010.
**Being present on the roadmap is NOT a commitment to deliver. Dates are subject to change, but we are working on both.