Not sure TBH.. But one thing I hope thru fix is natural language for apps.... E.g. Instead of saying 'flixter top movies'... I want to also work if I said 'Cortana, show me top movies in flixter'.... Currently that doesn't work. :-(
From the apps I have on my phone Wikipedia from Rudy Huyn, WPCentral and Nokia MixRadio are supporting Cortana. You see the apps if you bring up cortana and click "see more" than scroll down to the apps sections.