Looks like Google
finally releases a (edit: an improved) Geocoding service for the Google Maps API. Try it out here. I wonder how compares to the Yahoo Maps API Geocoding service that has been available for some time.
It would be interesting to see a street/address based geocoding service from OpenStreetMap.org. From data alone it is obvious that it would have more world coverage then Google Maps or Yahoo Maps Geocoding. At the moment they only offer geocoding based on "geographical object names" with help from Geonames.org. It should be quite trivial to write a street/address geocoding algorithm using the OpenStreetMap.org data. Half the world lives outside the data covered by Google and Yahoo! Geocoding - the exotic half.