iTunes RSS Issues

Here's a great post about iTunes issues with their RSS parser/namespace. (Note the best info is in the comments) Hard to believe that Apple would do this one:
iTunes sends only two HTTP headers: “Accept: */*”, and “User-Agent: iTunes/4.9 (Windows; N)” (presumably platform-specific). It does not support ETags, Last-Modified, gzip or zlib compression, or RFC 3229
. Anyone know how often Apple polls?