Since asking that question I discovered the Molex 015015xx27 series which comes in 2/4/6/8/10 inch lengths. I haven't used this because I'm sticking with the Gumstix CBL047 for now, but as far as I can tell it should be compatible.
Thank you for the recommendation. That is exactly what I am looking for. However, I could only find those particular ones in minimum shipments of 545 count. Maybe I just couldn't find the right distributor. Any help would be appreciated!
I've found them at two distributors:
 Element14 has the 4" version for NZ$8.10, MOQ of 1.
 Digikey has the 4" version for NZ$4.09, MOQ of 1, but is currently out of stock.
Unfortunately neither of those stock the longer versions.
Molex also have a list of distributors on their site . It always seems to be the way that distributors stock everything except the one part you need!
I used the e-CAM32_OMAP_GSTIX from e-con and tried streaming at 30fps through VGA. One of the things we experienced when using a longer camera cable with Gumstix Overo is noise. So, if you are streaming VGA @30fps then you will see this noise when the cable length is around 10cm. But if you stream it at lower speeds you wont see this. The cables with 5cm length work perfectly and I was able to stream VGA @30fps and do the encoding at 30fps as well.
IMHO, The parallel cable cannot carry long distances and it is recommended to go via a LVDS solution.