I believe the answer to this is "kind of". Some of the reasons that there wouldn't be a standard module/set of modules for these sorts of functions are:

1. different backends (e.g. are the user data stored in a database, a flatfile, etc.?)
2. different needs (e.g. session management, user history)
3. different intended environments, exposure, and audiences and thus different constraints/concerns

And besides, when it really comes down to it all you have to do is: get the username/password (or whatever), compare it to a value stored somewhere, and do something based on the result of this. A very small & trivial portion actually involves CGI.pm (namely, the creating login and post-login interfaces and grabbing CGI variables. Maybe.).

This being said, I've heard other monks around here talk about several other modules on CPAN that have further abstracted common web tasks into API's for the aspiring perlmonkey to work with.

Anybody care to mention any of these again?