At the recent QA Hackathon in Birmingham (which was great - many thanks to Birmingham.pm for organising it, and to the hotel for having a rubbish network so I actually worked instead of dicking around on IRC) I worked on my idea for the Comprehensive Perl $version Archive Network, or CPXXXAN for short, mostly so I can make jokes about hot module-on-module action.
It is intended to be a set of CPAN "mirrors" which only contain distributions which pass their tests on a particular version of perl, with their 02packages index files set up correctly so that if, eg, you go to the mirror for perl 5.6.2, you'll get DBI 1.604, which works, instead of DBI 1.607, which doesn't.
While you might think that this is pointless - the argument is that "people who don't upgrade perl won't want to upgrade modules" - consider that recent releases of some distributions now require perl 5.10, even though that's only just over a year old. 5.6.2 just makes a convenient test case.
In Birmingham, I tested it and got it all working on my laptop, using a subset of the data (specifically, distributions beginning with DBI or DBD). Now I'm building the 5.6.2 index for the whole of the CPAN. It's taking a very long time, but I'm not that concerned, as I'm unlikely to update the indices more than once a month. Even so, any Clues about how to make my SQL more efficient would be most welcome. See the schema and the query that figures out what the most recent passing distribution is and what modules are in it.
All the code if in my git repo, email me if you want access.