We know that Apple is aware of the data-annihilating Guest Account bug in Snow Leopard, and it looks like a fix is on the way. The latest 10.6.2 beta seeded to developers specifically addresses the issue, and throws in a few other tweaks for good measure. If you're staring at that Guest Account on the login screen with fear and loathing, sit tight. Hopefully this will all be resolved soon. [9to5 Mac]
