I just stumbled upon this awesome homebrew application a few minutes ago. For those of you with a R4 or other such device for your Nintendo DS you can now have Google Maps on your DS anywhere there is an open wifi connection available!
It doesn’t have satellite map support and no stylus controls, only the D-Pad and A/B for zoom in and out but it loads the map off the web so you have a fresh map wherever you can connect to the internet via WiFi!
Download Google Maps for the DS here!