What Are The Book Cover Art Dimensions For iBooks?

I'm completing my first book for publishing to the iBooks store, but so far I've not been able to locate what the dimensions should be for the book's cover art. I want to make sure we have a crispy, well-designed, high-res cover, so I'd like to know the specs.

If referring to a "Cover" to be included on a page of the ePUB book, then Michael of ZappTek (Legend Maker) indicates the limit is 740x560 pixels. If referring to external files used as cover art, most sites providing images for use in ePUB management applications like iTunes or Calibre which are typically limited to 500 pixels in height or less. The pages routine used by Apple will accept an image up to the size of your document page but then scales the "cover-image.png" file stored in the ePUB package. As an example, a "US Letter" Pages document (8.5" x 11") will end up producing a 400x517 pixel "cover-image.png" file in your final ePUB.

Also, some info here:

http://www.pigsgourdsandwikis.com/2010/09/on-using-pages-for-epub-part-1.html