I have just been alerted to an issue created on Southwest.com when a customer uses the FireFox add-in called Ghostery. Ghostery allows blocking of tracking tools, including Omniture (SC) specifically. What we are finding is that Ghostery is killing the Omniture code and is possibly causing the browser to fail to load additional .js files lower on the page.
Clearly a solution is to move the SiteCatalyst code lower on the page, but of course the potential here is for a much bigger issue if this type of functionality creeps into corporate firewall tools or becomes more widespread. Our technical groups here are currently working to resolve our issue, but if you haven't heard of or reviewed what Ghostery does, I highly recommend you alert your QA departments to this issue!
If you have any ideas or suggestions for dealing with this or more information on how Ghostery works, it would be greatly appreciated!