I think all registered users got it today.. check the Google Earth board (you have to be logged in to do so) for more info. it is a beta test, not the full product release, so "be aware" of that before deciding to download as it will wipe out your current Keyhole program. You can apparently uninstall Google Earth and reinstall Keyhole if you wish later.
Considering the email came from uptilt.com who are among other things "a leading provider of advanced email marketing solutions" you are wise to be concerned

but this one is legit.