Very nice thread on GIAC ECU tuning:

http://www.6speedonline.com/forums/997-turbo-gt2/142660-benefits-giac-flashloader-system.html

I believe GIAC is one of the most prominent/best selling ECU tuning shops in the US. I think it's nice that they are answering questions in public and make themselves available to scrutiny & challenge. The info posted is very interesting, for example the 2 different ways programming is done. No association, so please don't shoot the messenger. If you have any question feel free to post; there, not here.

GIAC is the company that "eclou" uses for tuning his Turbo and took it to ~ 190 mph at the Texas mile.