Well technically with the appstore coming out. GPS on 1st gen iphones isn't far fetched as long as apple lets developers use the dock port. Like with the PSP hacking community. All it would take is a gps chip and an app released through the store to enable you to have true GPS. Honestly the same could be said about having 3G. Although I'm not sure apple would let someone make a 3G chip for the iPhone dock port seeing as it would make some people not upgrade. heh.
One more thing. They have different versions of iPhone extended batteries that also plug into the port. It's actually kind of cool. And with the 3G phones coming out this may be a very nice accessory. You don't have to use it all the time but if you know you are going to be away from an outlet a long time you can carry it with you (like an extra laptop battery or even cell phone battery back in the day when you could change those out............by yourself...........) and never have to worry about battery life and 3G.
Some links:
FastMac iV iPhone Battery Pack - Includes a light (for seeing in the dark and taking pictures in dark places) and ability to charge other devices while plugged into iPhone. Even charge another iPhone... Can also plug into dock in order to charge both the iPhone and pack without removing. (pre-order status)
Kensington Mini Battery Pack - Doesn't last as long as the previous but is very small and only sticks out the bottom instead of adding to the back.
Kensington Battery Pack and Charger - The full blown brother to the previous model. This guy would be more for carrying around in a bag (like with your laptop) and plugging in when you can sit down somewhere but don't have access to an outlet.
Richard Solo Battery Pack - This one is like the mini pack above but a bit larger. Good for keeping in your car or a backpack just in case. Also has a longer life than the mini.
iPowerRush - The super cheap version of extended batteries. Lol... This thing probably works but you have to buy 6 AAA batteries to put inside it to charge your iPhone. After a few uses it would end up costing you more than just buying one of the other products but I figured I'd give the option.
Also you will probably be able to use your phone's 3G capability to give your laptop internet anywhere. (you can already do this with edge).