Most of the information in Yahoo Local and Google local come from Data Providers and Aggreators (Like Yellowpages, InfoUSA, Experian, Acxiom and Localeze to name a few). Therefore if your information is in Yellowpages database it is likely your business will show in Google Local, Yahoo Local or Live Local (formally know as MSN local).
I have some links that will allow you to submit your business for free. On my website if you are interested. Good luck!

P.S. I know all of this becasue I am a Local Internet Advertising Consultant

P.P.S Almost forgot the link it is Internet Marketing for Local Business - Local Advertising - Small Business Marketing