This question was posted in response to the following article: http://help.adobe.com/en_US/aftereffects/cs/using/WS3878526689cb91655866c1103906c6dea-7f7c a.html
Might be worth highlighting that a CMYK .PSD will import into AE but will not show the layers. Maybe AE CS7 could have a warning on import that the .PSD is CMYK. I know its a simple error but it would save users a lot of time having to go through help files until they discover why the layers are not showing up
That information is already given on this page, in the section with the heading "Color modes".