Encrypting File System Options for Mac OS X?

fieldmouse asks: "I recently had a laptop running Mac OS X stolen. Despite the fact that I got it back, that incident has me looking for an encrypting file system for Mac OS X; preferably one that would create a psuedo drive that I could unlock once when I log on. Anybody have any suggestions?" About 2 years ago, Ask Slashdot did the Linux version of this question. Has this gap been filled in Apple's latest OS offering?