Card titles are behaving erratically under Mac OS 10.6 and Scrivener 1.5.2 and 1.5.3. I’ve made a screencast showing the behavior and uploaded it at screenr.com/6t8
It appears to be some sort of unicode issue… the care titles change when switching to/from other windows (browser, or even just the About Scrivener dialog box) or when switching between documents within Scrivener.
Did you check your FontBook? I remember some people mentioning that some of their fonts had been corrupted upon their system update to 10.6, which I think produced this effect.
This seems to be a bug in Snow Leopard itself, whereby the update is duplicating and corrupting certain fonts (including Courier, which is used in the corkboard). Please see the following threads, which describe the problem and explain the solution (Tarkine’s information is particularly helpful).