Based on the chart posted by Trail Rider - there definitely are different video pinouts. So not all 3.5mm video cables will work. The Archos cable I had did NOT work.
A good option for those wanting a more portable/slick connection are the insten retractable ipod video cables. I bought mine from eforcity.com, and it worked great.
http://www.eforcity.com/dappipodda14.html
The only knock on this cable is that the 3 individual wires on the end are as thin and fragile looking as they are in the picture. But I've had no problems with the cable - and the picture is great. Unlike the other 2 video cables I made, there's no hissing from the audio. If you decide to buy the insten retractable, either froogle search or ebay for a better price - or google for an eforcity coupon. I think I payed $3.50 shipped with a coupon.