The way that Google handles canonization has, frankly, angered some in the SEO community for quite some time. I guess we can call it dramatic irony that GoogleGuy's own blog seems to be having some canonical issues.
From a WebmasterWorld supporters thread:
To me it definetly looks like Matts site is on the verge of a Canonical url problem.
Ok - it depends on what datacenter you are accessing but if you do a domain.com search and a www.domain.com search Google now has these listed as seperate pages. Also on some DCs the domain.com search is now url only......
Also do a site:domain.com -www for Matts site.
We'll all have a good laugh if it gets hijacked. Meanwhile, I can't say this is a bad thing, especially if it prods Google to put more resources into solving this issue once and for all.