I'm dubious that any campaign of this sort could be anything other than marginally effective. The real holdouts that I'm worried about aren't staying with IE6 out of ignorance, it's a matter of financial necessity. Internal and business-specific apps are holding back a lot of these upgrades. If you have to choose between a $50,000+ development investment and staying on an outdated browser, most IT departments are going to maintain the status quo.
This is why I think Chrome Frame is such a good solution- you get all the benefits of a modern browser, without having to immediately invest in updates to essential apps. Of course this also runs the risk of being (understandably) stymied by Microsoft marketing FUD.
Chrome Frame is great, but there needs to be an official, Microsoft-blessed "IE6 frame" to deal with this. From what I understand, the compatibility mode in IE8 isn't good enough. People need to move onto the new browser and use a modern rendering engine by default instead of retrofitting the old browser.
This is why I think Chrome Frame is such a good solution- you get all the benefits of a modern browser, without having to immediately invest in updates to essential apps. Of course this also runs the risk of being (understandably) stymied by Microsoft marketing FUD.
::sigh::