It's not a surprise. Google must register such a domains otherwise they will get abused. It won't be a problem since Google is a ICANN domain register.
Google owns lots of domains, including domains for services they haven't released yet, it's really interesting.
Checking to see what they register is a good way of getting insider information. Domain names are a key part of understanding what a company is up to. Know how they register (direct, proxy, "private", etc) and look out for new registrations to keep ahead of the crowd.
But thats ok since you can make all the google.yoursite.com's you want! Actually a while back (way way way back), I made a site like google.blogzine.com. I started getting worried thinking about the lawsuit that I'd be facing.
On a slight side note, they do not own the Gmail.pl this domain was snatched up by a Polish young artists association-type group. Google wanted to go to court over this but I think they gave up.
They have been doing that since they started, and they should honestly. I know I would if I had the funds available.