What navigation software will work with the iphone?

i know it does not have built in gps - but what software will work via bluetooth with external gps?What navigation software will work with the iphone?nothing. thats why no one has one...well, except you.What navigation software will work with the iphone?the iphone hasn't any internal gps but next year will be launched an iphone with gps. you can use any external bluetooth gps