Just my two cents:

Can anyone provide a definitive reference on the meaning of version 1.0 in the Perl world, especially for CPAN modules?

I've always thought it was pretty arbitrary, that is, TIMTOWTDI...

advice on how a CPAN module should advertise that it is stable, well-tested and not experimental.

That's a good question. Personally I would make a note in the POD and/or Changelog if a version is stable - though I tend to only release decently-tested stuff anyway. If I was giving advice to someone else, what you quoted from SemVer is probably good advice. And I wrote a bit about judging the quality of a CPAN module here. (Update: hippo also makes a good point here.)

Oh, and other cool Perl versioning references you may know of that are not mentioned here are also welcome.

My bookmarks on versioning modules currently are: 1182640 and 11114665.