I'm probably not the first one to notice this, but you can actually use Google Earth anonymously (upon first glance at least) over Tor. It seems all the traffic (downloads of maps and textures etc.) goes over port 80 (http) and 443 (https), which can easily be anonymized with Tor (read an older post of mine for details on Tor).
Just type
export http_proxy=http://127.0.0.1:8118/ export HTTP_PROXY=http://127.0.0.1:8118/
and set up Privoxy and Tor correctly, then start Google Earth in the same xterm and you're done. I haven't looked closely at the protocol Google Earth uses (any articles available on that?) but upon a quick glance in Ethereal / Wireshark all traffic is torified, not even DNS requests are leaked. Technical explanation: the Google Earth binary uses libcurl internally, which honors the http_proxy environment variable.
However, that's not a guarantee that you're 100% anonymous, as Goole Earth could send some unique identifier (e.g. MAC address, hard drive ID etc.) to their servers which would spoil your anonymity.
Btw, I actually discovered this accidentally because I have the above HTTP_PROXY lines in my .bashrc, so most of my HTTP traffic is anonymized by default...