Google Chrome OS, their cloud based operating system currently being tested, provides click to call functionality on all Google blended local search results as well as phone numbers visible in general search results or on web pages. The call is connect over the Google VOIP network. The functionality is available on Google apps on smartphones but not in any other current desktop environment (unless you are using the buggy Skype plug in).

The click to call functionality is “turned off” if the user does not have a Google Voice account or is logged in as a guest.

As long as the number is formatted with parenthesis i.e (716) 204-1297, the click to call functionality is available across the web and not just on Google products.

Click the image to view the original Chrome OS full screen shot:

Several months ago Google was testing an enhanced Google Places Dashboard that included tracking of calls by mobile devices using Google Maps for Mobile.
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Given the lack of an industry wide call tracking standard for local it appears that Google will be going it alone in providing call tracking information from software, services and devices that they control.