Is anyone aware of the licensing/costs to embed the Google Earth plugin (and manipulate it with the API) on a site that has a commercial aspect to it? (i.e. charges users for a service that is partially related to the mapping function).
I don't want to get all "Get off my lawn!" on your ass, but really-- if this is important to you, you ought to spend more than a half an hour on it before asking someone else to do the research for you.
If it's not important, well then, all the more reason not to fob the research off on other people.
Sheesh.
Anyway, the answer to your question is in the TOS (http://code.google.com/apis/maps/terms.html)
9.1 Free, Public Accessibility to Your Maps API Implementation. Your Maps API Implementation must be generally accessible to users without charge. You may require users to log in to your Maps API Implementation if you do not require users to pay a fee. Unless you have entered into a separate written agreement with Google or obtained Google's written permission, your Maps API Implementation must not:
(a) require a fee-based subscription or other fee-based restricted access; or (b) operate only behind a firewall or only on an internal network (except during the development and testing phase).
So sure, you can use it on a commercial site-- as long as you are not (directly or indirectly) charging for the map access.
For example: suppose you have a site selling CDs. You could use the Google Earth/Maps API to show where the CDs were recorded, as long as this part of the site is freely available to all comers.
I did find that ToS but I wasn't sure that "Maps API" and "Google Earth Maps API" were interchangeable. I'll dig deeper...
My intention is to provide a map based preview of some real-time data as the entry point to the service (publicly accessible, no charge) and then to charge for extended information/alerts. It sounds like that should be acceptable use.