Who’s not getting gzip?

From the referenced Google Code Blog <a href="http://googlecode.blogspot.com/2009/11/use-compression-to-make-web-faster.html" rel="nofollow">http://googlecode.blogspot.com/2009/11/use-compression-to-ma...</a>:<p><i>Anti-virus software may try to minimize CPU operations by intercepting and altering requests so that web servers send back uncompressed content. But if the CPU is not the bottleneck, the software is not doing users any favors. Some popular antivirus programs interfere with compression. Users can check if their anti-virus software is interfering with compression by visiting the browser compression test page at Browserscope.org.</i><p>Serious? Anti-virus software that is doing that is acting almost like malware doing what the user didn't ask it to do. Does compression have any even minor security implications that would legitimize this? And anyone know which anti-virus does this?

As an exercise, I heard that a toolbar company (who shall remain nameless) ran an experiment to record a client-side hash of the DOM of some particular static pages and found that something like 30%-40% of users had modified or tampered results. Some of this could be spyware, some the antivirus add-ins, but still shockingly high for static content I thought.

Those are scary numbers. Anybody know of rules to force it to on, without breaking clients that really don't support it?