Nav DVD update?

I have an '03 Denali XL with factory NAV radio which came with an '02 DVD. Does anyone know if there is a newer DVD available and if so is it a worthwhile upgrade and where is best place to get. Thanks.

I just ordered one from GM, and the one they sent me is on '02. I'm guessing this is the newest one.

I was at the Dealer today and they have Version 3.0 available but it was $365! Has anyone tried reproducing the DVD and sharing the costs with other Denali owners?
Now you know better than to post something like that! ;)

But I will say this--it can be, and has been done; PM if you want more info...