So we have already confirmed the next generation 3G iPhone will have GPS feature. But if you want GPS function on your old iPhone?
The new solution is from some people at ipgsd which consists of a cable allowing your jailbroken iPhone to connect to a GPS receiver GPS – in this case Holux M1000b.
Just the cable itself will cost you $16, but expect to pay $100 for the Holux M1000b package which includes the cable.
Here is a video of the iPhone GPS demo doing real time updates: