The world saw Alexa and Cortana work together for the first time today in a demo at Microsoft’s Build conference being held May 7-9 in Seattle.

The partnership will make the assistants available on each other’s devices. The demo shown today was limited to things like hailing an Uber ride with Alexa on a Windows 10 PC or checking your schedule with Cortana on an Amazon Echo.

The demo was set in a scenario with an Echo speaker in the home and Cortana on a PC at work because Amazon is the most popular speaker in U.S. households, and Cortana, which is available on hundreds of millions of PCs running Windows 10, is the most popular assistant in the workplace.

When Alexa was asked “What do you think of Cortana?” on a Windows 10 PC, the AI assistant responded “I like Cortana. We both have experience with light rings, although hers is more of a Halo.”

Alexa with Cortana and Cortana with Alexa will first be made available in limited beta, said Cortana general manager Megan Saunders.

“We want to make it possible for our customers to be able to get the most out of their personal digital assistants and not be bound to a single walled garden and for developers to work with the maximum number of users,” said Microsoft CEO Satya Nadella about the company’s view of a multiple AI assistant world.

A progress report on the partnership has been long overdue.

Announced last summer, the Alexa-Cortana partnership was initially scheduled to begin by the end of 2017, according to a joint release by the two companies.

Since the partnership was first announced, Amazon has extended Alexa deeper into the workplace with Alexa for Business and by bringing Alexa to personal computers starting with Lenovo, Acer, Asus, and HP PCs.

Cortana has been working on skills especially made for the enterprise, Cortana VP Andrew Shuman told VentureBeat in an interview last fall. New changes to make Cortana more powerful in the workplace are on the way, Cortana head of product Javier Soltero told VentureBeat in an interview.

“It’s been a very informative journey for both companies and really understanding what each of us brings to the table, how we can help, where is the overlap between our users and the interests that they have, how can we provide experiences that are great, and I think we’re making great progress on that,” Soltero said last month in an interview with VentureBeat about the future of Cortana.

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