Mine is not an exact pumpkin, but if you leave some of the flesh at points, you could carve it like this and have the Apple appear 3-dimensional. If you want more ideas, check out this site:

http://www.pumpkingutter.com/
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MacBook 2GHz Intel Core 2 Duo w/ 2GB DDR2 RAM & 120GB SATA 5400RPM HDD
Canon Rebel XTI
Google Cr-48 Beta Laptop