November 2, 2009 -- 

Apple has publicly acknowledged a rare but nasty data-destroying bug related to using the Guest account in Snow Leopard. The bug appears to be associated with having a Guest account already set up before you upgrade to Snow Leopard. While there is currently no fix available, we hope to see one in 10.6.2. To learn more, check out my TidBITS article, Apple Acknowledges Guest Account Data Loss Bug. [This bug was fixed in 10.6.2.]

—Doug McLean