My GPS navigation system has a DVD player of its very own hidden in the car. I just found it today and popped out the disk.
Here is what it looks like.
I can read it in my computer and the version file matches the DATA ver.07.1 printed on the label.
The newest version from the dealer (10.1 with 11.1 due out "Fall 2011") costs $200. I don't want to spend that much. Also, I've heard some people had their map shifted by 100ft or more so the previous locations did not work and so the system gave wrong directions after the upgrade. (Just a rumor.)
With the 2009 Prius you are looking for a GEN 5 DVD. The GEN is your hardware generation and it doesn't ever change for your car.
Some people are hacking these DVDs to unlock the GPS system so you can use it while in motion, and so you can play ordinary movie DVDs that show up on your NAV screen.
Both seem like bad ideas, but I like hacking things just to see if it can be done. For example, can I turn on the reverse video camera feed while moving forward? I totally want to do that.
I wouldn't watch movies while driving, but there are times when I start rolling and I have one more number to enter for an address in the GPS and the system shuts off. I hate that. I would like to be able to override it.
Google for instructions, but heed this: if your Prius accelerates without warning and kills you after you hack it with a file downloaded from some Russian or Chinese web site, you'll have only yourself to blame.