I just noticed some visitors to this website were reporting a user agent like this one: "Mozilla/5.0 (X11; U; Linux x86_64; en-US) AppleWebKit/532.9 (KHTML, like Gecko) Chrome/5.0.307.0 Safari/532.9"
See that? That's Chrome 5.0. I went to check the latest version of Chromium at UbuntuUpdates and here it is, 5.0.307.0. It's only in the Ubuntu Chromium Daily Builds PPA though.
I'll give it a bit more time before trying it... The official version is still 4.0.249 in the Google Chrome repository