As ZDnet points out, and one can see today by clicking on the Google logo:

Google lands on Mars Posted by Garett Rogers @ 8:35 pm

"Tonight I noticed that mars.google.com now has a CNAME record that points to www.google.com. This usually means that something is about to happen with that subdomain — with the exception of calendar.google.com of course. So I started digging and you will never guess what I found — a Google Maps type application that lets you view Mars. This service is called 'Google Mars.'"