To speed up their site (a bit)?
http://www.askapache.com/htaccess/ap...eed-etags.html
"By removing the ETag header, you disable caches and browsers from being able to validate files, so they are forced to rely on your Cache-Control and Expires header. Basically you can remove If-Modified-Since and If-None-Match requests and their 304 Not Modified Responses.
Entity tags (ETags) are a mechanism to check for a newer version of a cached file. "