Why are you giving Google, of all companies, a pass because they just "copied from a tutorial"? Google is probably the least deserving company in the entire world of the engineering ignorance defense.
Think about it: Google knows enough about the inner workings of IE to create Chrome Frame. How in the world is not knowing enough about how P3P works in IE an excuse?
Google said it isn't possible to create an accurate P3P header that describes how they use cookies. Having previously tried to parse the standard document, I'm inclined to believe them.
If that's the case, the responsible course of action is not to send a P3P header at all. Sending a deliberately false one to circumvent third-party cookie restrictions is simply not cool.
If they can convince people to install Chrome Frame, I'm sure they can figure out how to tell people to enable 3rd party cookies. My guess is they'd have a lot harder time explaining why the user should do that.
And yet they spent all that time doing it ... Seriously, who is Chrome Frame for if not the average user? And they inform you about it as soon as you visit google.com in IE.
I suspect you're right and the uptake isn't what they wanted, but that's not really a valid reason for them to work against the browser settings designed to protect a user's privacy.
They can't provide a P3P header saying that won't let 3rd parties track you with it? That would "Break" their +1 functionality? I'd like an explanation of that.
Think about it: Google knows enough about the inner workings of IE to create Chrome Frame. How in the world is not knowing enough about how P3P works in IE an excuse?