Personal navigation and GPS-aided turn by turn directions are moving from hardware to software. Given that the new iPhone enables turn by turn navigation to be integrated into third party developer apps and that TomTom is going to be on the iPhone, the days of separate PND hardware devices are likely numbered.

While some such devices may continue to sell, consumers will see fewer and fewer reasons to buy them (and spend the additional cash) now that smartphones will be largely as capable as PNDs and have broader utility. Several next-gen navigation apps have already emerged in the post 3.0 iPhone world: 

• NIM's Gokivo (which uses Yahoo! search results) provides voice-guided navigation, but requires an in-app purchase of $9.99 for a one month subscription. (Pricing was just simplified; there were previously three options.)
• Navigon’s Mobile Navigator (Europe) app with NAVTEQ maps.
• Sygic for Australia, New Zealand and Southeast Asia.

The improvement of navigation on smartphones combined with the move of a group of companies to provide their software on the iPhone platform will mean that eventually the entire industry will move in this direction.

Recently RIM also acquired "connected" PND platform Dash. So one would assume that many of these same capabilities will shortly come to BlackBerry devices. (I was just reminded that MapQuest provides turn by turn directions on BlackBerry devices currently.)