The new Toyota Venza and the upcoming 2010 Toyota Prius are coming with the new generation 5 Navigation system.
As far as updates, each generation of the navigation system has their own update discs. (Different software, so different updates. You can't take a disc from a Gen. 4 system and install it in a Gen. 2 system, for example...) So, if there's a new update for your navigation system, it would depend on what type of navigation system you have...
If you're in Europe, you can find this info out for yourself at
http://www.toyota-mapupdates.eu/ , but in the US you'll have to contact your dealer's parts department for more info. (Perhaps there aren't enough new updates in your local area to make upgrading worth the approx. $200 for a new DVD.)