This is a great plugin, and thanks for providing it to the WordPress community. It appears that 0.9.10 has some bugs, too. As someone else pointed out, it fails to work with Internet Exploder, but before I found that post with the fix, in my attempt to figure out what was wrong, I noticed that Google Mapper 0.9.10 creates a page that fails XHTML validation. Unless I happen to find and implement a fix, you can see the the validation errors here.
Both of these errors are within the code the plugin generated, and as far as I can tell, there’s nothing I could have done in the plugin configuration to cause these errors.
In case I do happen to fix these on my own, the errors given are below (the line numbers won’t mean anything outside of this specific page, of course, and I’ve replaced the tag chevrons with  to keep anything from being rendered, and I’ve bolded the character that the validator highlights in each error):
Line 68, Column 6: document type does not allow element “h3” here; missing one of “object”, “applet”, “map”, “iframe”, “button”, “ins”, “del” start-tag.