As an avid Google mobile fan (Google SMS anyone?) I am happy to announce the availability of Google Traffic Maps for Mobile. This service provides detailed directions, integrated search results, easily movable maps, satellite imagery and real-time traffic for 30 major cities on your cellphone.
Google Maps for Mobile is mostly free. It does require java browser support, so some kind of data plan will likely be required by carriers. This is an extremely good alternative to those who want some GPS goodness but don't want to drop a G on a GPS unit for their vehicle. To access this service, simply point your cellphone browser to www.google.com/gmm.