Although this does not answer your question directly, you can also consider the following two options:

If you do not need very high frame rates, search for a module like the one below:
http://www.sparkfun.com/commerce/pro...oducts_id=9334

All data is passed through serially, so you do not have to worry about camera capture and compression.

Or
http://surveyor-corporation.stores.y...lowlicamo.html
You will have to provide camera timing lines. The interface is parallel.

EDIT:
Example of the first one with an Arduino at 640x480
http://gizmologi.st/2009/04/taking-p...-with-arduino/