"Google is moving its blogs to a new domain to help people recognize when they're reading an official blog from Google. These changes will roll out to all of Google's blogs over time. The previous address will redirect to the new domain, so your bookmarks and links will continue to work."
A long time ago, many people thought that this is an official Google blog and I had to keep explaining that the blog is not affiliated with Google. I added more and more disclaimers, but that's still not enough for everyone. Now that Google's blogs move from blogspot.com to googleblog.com, it's much easier to tell things apart.