I know it doesn't directly answer your question, but for most log analyzing needs, Analog does some great work. (it doesn't help you if you're trying to do more specific reporting than what they support, but it does a great job for those times when management wants 'metrics' and isn't specific in just what they want.)

Oh -- and the apache logs are in what's known as 'common log format'. Searching for that, I found Regexp::Log::Common and AnyData::Format::Weblog, neither of which I've used.

Update: Also not a CPAN module, but you might want to see the sample chapter from Perl for Web Site Management