I got an email reply from Graham Barr that this format link does work: http://search.cpan.org/dist/libwww-perl. From the PM side, there are a couple of gotcha's:

• you have to use the distribution name which might not be the commonly used name (eg: libwww-perl rather than LWP
• you have to remember that distribution names use hyphens rather than double colons (eg: XML-Parser)
• don't forget about case sensitivity

Given all this, it's not hard to see why the [cpan://name] links go to the search function but if you get the module name wrong (eg http://search.cpan.org/dist/xml::parser) then search.cpan.org falls back to search mode anyway.

So, perhaps the implementation of the [cpan://name] links should be fixed to change '::' to '-' and then point to search.cpan.org/dist/name

There is a big difference between a distribution and a module. Substituting :: with - will not work for most modules.

I would like to see the cpan links to link to http://search.cpan.org/perldoc?module

right now that is an issue for modules that don't have pod, but we can fix that

Yes, there is a big difference and the perldoc-style link seems to work well. It would be even better (you just knew that was coming didn't you) if it wasn't case-sensitive or if it redirected to search on failure. Eg: http://search.cpan.org/perldoc?LWP::Useragent simply ends up saying 'Not Found' simply because 'agent' was not capitalised.

Anyway, I've ended up getting sidetracked on the details of linking from PM to search.cpan (which arguably isn't broken anyway) when what I'm most interested in is setting up an infrastructure on PM so that search.cpan can link to discussion forums. I think the best approach (at least initially) would be to base the structure around distributions on the PM side.

--
perl -pew "s/\b;([mnst])/'$1/g"

I am considering a google style lucky option, but it is not high on the todo list right now