Tonight's hackathon session with Ingy was very enjoyable. I volunteered to be the guinea pig for his soon-to-be-released much-refactored pure-perl YAML 0.50, which has been sitting on the YAML-Dev subversion repository for months, but Ingy was afraid of it breaking existing users.
The fear appears well-founded, as both SVK and Module::Install had incompatibilities (something to do with autouse.pm -- I'll spare you the details), but we had them squashed, so expect YAML 0.49_xx test releases appearing on CPAN today.
In addition to that, I mentioned that many other languages had decent Syck binding for ages, yet Perl 5 only had a randomly-segfaulting YAML::Parser::Syck and no dumper bindings. Thanks to SWIG and Ingy's guidance, I coded up a working implementation of YAML::Syck in a few hours. I think a fast lightweight YAML library will really benefit interoperability, and with some more polish (i.e. lifting more scary bits from Storable.pm) it may even be core-worthy in the future.
As Pugs had YAML parsing support for quite a while now with the eval($yaml_string, :lang<yaml>) builtin, I look forward to carry the same sort of proper YAML loading/dumping support to PIL.Native runcore sometime this week.