Yes you are correct that the Storm does have GPS, but Verizon has locked out the functionality of it towards 3rd party apps. In other words, GPS works great with VZW Navigator service, but will not work with any other third party GPS apps such as Google Maps.
Not by my liking but it goes hand in hand with the same reasoning as to why VZW blackberry's do not support the Wi-Fi feature that other carriers BB's do.
Thay want to market and push their own services.
I myself would prefer Wi-Fi over GPS any day of the week.... :-(