Yahoo! Address Book API - YDN
You can know use an API (with BBAuth) to get contact Yahoo account contact details. There really is no excuse now for still using the password anti-pattern.
YQL now supports microformats! (Yahoo! Developer Network Blog)
Yahoo's RESTful query language can now parse microformats. This is excellent news ...although I'm personally finding it tough to wrap my head around the documentation. It's certainly trickier than hKit but then, it's almost certainly more powerful too.