There are four pieces to this:

- the road map you see in Google Maps / Earth. Anyone can suggest edits to this by drawing new / changed roads, and there's a review process for these changes (it works, I've edited several roads near me and the changes have been made to the main map, with emails advising of the progress)

- the overhead satellite imagery in Maps and Earth, which is updated regularly and the URL mentioned above shows what imagery was updated

- the low-altitude aerial imagery that you see when zoomed in to the satellite imagery in certain areas. This is also updated regularly but I'm not aware of a definitive list of covered areas

- the Street View imagery collected by car / trike / backpack. Updated imagery doesn't seem to be announced, from what I've seen, but entirely new coverage of an area is often promoted on the Google Maps blog.