http://earth.google.com/support/bin/answer.py?answer=21414&topic=-1
"Google Earth acquires the best imagery available, most of which is approximately one to two years old.
We recently launched our new Primary Database which includes:
- 15m imagery for the entire globe
- 90m terrain elevation mode data
- Updates to many US cities
- Major international expansion including, but not limited to, all major Canadian and Australian cities, Santiago, Buenos Aires, Rome, Naples, London, Luxembourg, Paris, Toulouse, Valencia, Barcelona, Lisbon, and Athens.
"
"ot all cities are covered in high resolution (where you can see individual buildings and cars) detail. We have more imagery of the United States than other countries currently. And because the imagery comes from a variety of sources, and is mosaic-ed together, it is difficult for us to specify the date of a city or region (a single city may have imagery taken from different months).
We are adding high resolution coverage continually, but we are not able to tell you when a specific area will be covered. The best way to find out if your area of interest is covered is to download the free version of Google Earth and check it out for yourself (Google Earth, Google Earth Plus, and Google Earth Pro share access to the same database)."