From the gmaps site [1]:
Mobile GMaps is a free piece of software that displays Google Maps and MSN Virtual Earth maps and satellite imagery on Java J2ME-enabled mobile phones or other devices.
Mobile GMaps is distributed under the Attribution/NonCommercial/NoDerivs Creative Commons license. You may download, use and distribute the application free of charge for non-commercial purposes. You may NOT use it for any commercial purpose.
Have a look at the documentation to see what phones are supported.
[1] http://www.mgmaps.com