In August 2005, Matt Cutts, the head of search quality at Google, launched his blog at http://www.mattcutts.com/blog/. Notice, if you click on that URL, you are redirected to http://www.dullest.com/blog/. Why? Well, Matt explained that he was to switch things around, with a new name, new design, etc.
But the main thing, he is using a 302 redirect, which is a temporary redirect. When moving domains, Google almost always recommends using a permanent redirect, 301 redirect. But since Matt said this is a possible temporary change, he is using a 302.
If you read through the comments, you might notice Danny Sullivan's comment where he said "Why do I suspect some ultra-secret Google we get 302s right test is going on." Matt Cutts replied soon after saying:
Danny, my site makes the perfect guinea pig. I laughed when Greg Boser got everyone to link to mattcutts.com instead of http://www.mattcutts.com. He was trying to mess me up and cause duplicate content hijinks, but little did he know that I was the guinea pig for the www/non-www setting in the webmaster console.
Nice to have Google experiment on their own stuff when changing or investigating issues.
Forum discussion at Sphinn.