The only way that the CASPA schematic can be correct is that it uses a top entry connector. Is this true?

In practice on the Caspa boards: yes.

The "details" tab on each product page at provides key information and connector information for each Gumstix product.

For example, the details tab on the product page for either Caspa board shows the 27-pin connector number to be "502250-2791". A quick search on the net confirms that this is a a "top and bottom contact" connector. 

For the Caspa boards, a technical information page is being developed in the User Wiki here:

which states "Insert the white ribbon cable contact-side-up into the Caspa connector and contact side down into the Overo connector."

This advice confirms your determination that the contacts on the top side of the 27-pin connector on the Caspa board should be used.

ie when the white ribbon cable is connected into the Caspa board, you should NOT be able to see the blue end.

Gumstix Engineering

via Don Anderson