As you might expect, Cortana is baked extensively throughout the OS, with the ability to control features such as appointments, messaging, opening apps, changing settings, and the like. But Microsoft repeatedly highlighted Cortana's abilities beyond simple voice interactions.
Cortana has extensive learning capabilities, with the ability to monitor interpersonal relationships, frequent locations, personal interests, music tastes and plenty more. In one demo, Windows lead Joe Belfiore showed how Cortana had autonomously flagged a news article that it thought would be of interest to him - an article mentioning that Joe himself was revealing Windows Phone 8.1 in San Francisco.
In a further demo, Belfiore revealed that he had given Cortana permission to read all of his emails, which resulted in the device asking him if it should monitor status updates for his Alaska Airlines flight.
In a simple voice interaction demo, Belfiore demonstrated natural language usage to set alarms and check his appointment schedule. In his conversation with Cortana, she set an appointment and notified Joe of a possible scheduling conflict. In Siri-like fashion, Cortana was also able to show appropriate results when looking for a Mexican restaurant in Palo Alto, California, and then narrowing down the search to find only those restaurants which take reservations.
Cortana has a sense of humour too, for example, likening her appearance - a dual-ringed circle - to a doughnut, among other things, as well as thanking Jimmy Fallon for facilitating her TV début a few weeks ago.
Initially, Cortana will be restricted to Microsoft and a handful of partners, but the company eventually plans to offer APIs that will allow developers to bake Cortana interactions and functionality deep into their applications. Joe demonstrated the kind of integration that Cortana can provide, by asking the device to remind him to ask his sister about her puppy the next time he speaks to her. Much later in the keynote, his sister 'unexpectedly' called, and on the incoming call screen, there was a note reminding him to ask his sister about her new puppy.
Cortana looks pretty good in action, but Microsoft is launching Cortana as a beta only for now, and - initially - in the United States only. Further down the line, it will expand to the United Kingdom and China, and other markets beyond that, but the company has not clarified any timeframes yet.
Top image via Microsoft UK