Has anyone had the chance to try out the new McAfee PGP disk? It seems pretty straightforward, allowing for the creation of encrypted "drives" using the CAST algorithm. Is anyone aware of any security flaws with it?

Make sure you get the latest version. The version released in May or June had a bug in it (bug was only in the Windows version, the Mac is OK). The new version re-encrypts old PGP disks to fix the problem.