Piwik 1.2.1 reports IE with Chrome Frame as pure Chrome. Just sayin’.
I’m playing with Piwik 1.2.1 – it’s a very nice tool, but it has a browser identification quirk that varies from the behavior of Google Analytics. I was running a copy of IE 7 with <a title="Chrome Frame site" href="http://www.google .com/chromeframe” target=”_blank”>Chrome Frame, and Piwik was reporting those visits as coming from Chrome. That is, Piwik seemed to recognize / record no difference between true Chrome visits and visits using IE with Chrome Frame – all were lumped in the same bucket.
In contrast, Google Analytics reports Chrome Frame usage as coming from “IE with Chrome Frame.” Use of full-on Chrome is reported as “Chrome,” so that you can really differentiate between the two configurations.
By the way, you should also bear in mind that both Piwik and Google Analytics are just reading the agent string header passed by the browser. If a user has Chrome Frame installed, it shows up in the agent string, even if the add-on isn’t currently active (that is, even if the visitor isn’t actually seeing things rendered by Chrome Frame). The only way to get Chrome out of the agent string, and have the browser present to Piwik / Google Analytics as plain old Internet Explorer, is to uninstall Chrome Frame.