Mapstraction Goes Testing
A One Stop Testing of all three Mapping API's Google, Yahoo and Microsoft
It's in early development at present, so this is alpha.
Looks as it needs a little attention so sites provide more functionality but this seems to be bringing the coding side together. Looks promising, updates here when and how.
This site communicates with Google maps version 2, Yahoo maps version 3 and Virtual Earth version 2 (version 3 soon).
A similar site was blogged by mapperz called rockstarapps.com
(back in 31 October 2006)