Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
There is another solution is from IGPSD , and they have already selling it since July.
It cost only 16USD , and it works with Holux GPS.
You can get it at http://store.igpsd.com/
some demo video has listed on their blog
http://igpsd.wordpress.com/2008/09/22/first-gps-program-for-iphone-2g-20-and-21/
http://igpsd.wordpress.com/2008/10/08/iphone-version-20-navigation-with-freemap-for-israel/