As Fortune’s Adam Lashinsky put it, “Hell has frozen over.”

The two technology titans have long been at each other’s throats. But they put aside their differences for a public event at a San Francisco auditorium to pitch their products — and, of course, make some money.

After talking about the company’s new iPad, Phil Schiller, Apple’s chief marketer, described how new apps created for the device can help with workplace productivity. It was then that Schiller said he would like to bring out a few developers to the stage to show what can be done.

And out came Microsoft.

“Yeah, these guys know productivity,” Schiller enthused to a crowd that seemed shocked to see a Microsoft executive striding across the stage. After a few deep breaths, the audience applauded the entrance of Kirk Koenigsbauer, corporate vice president for Microsoft’s Office division.

Without noting anything unusual about his appearance on stage except to say, “It’s a thrill to be here today,” Koenigsbauer quickly started showing off the latest version of Microsoft Office for the new iPad Pro. It was like just another presentation, except it wasn’t.

Apple generally keeps its events limited to Apple executives — who invariably brag about all the new devices — and friendly startups that show how their apps work just great with Apple’s products. It’s one big commercial.

It was only a few years ago when Apple CEO Tim Cook reportedly said about Microsoft’s Surface tablet, “Our competition is confused. They’re turning tablets into PCs and PCs into tablets.”

So what happened?

Under Cook’s leadership, Apple increasingly pushed into becoming a technology supplier to businesses. In contrast, Steve Jobs, his predecessor, focused most of his attention on consumers.

In example of the new philosophy, Apple (AAPL) last week said it had partnered with networking giant Cisco (CSCO) to sell iPhones and iPads to corporations. And last summer, it joined forces with IBM to make business apps for iOS devices.

By inviting a Microsoft (MSFT) employee to demonstrate the popular Office software on a new iPad, Apple hoped to convince corporate buyers that its gear is business-friendly. Having a Microsoft employee doing the presentation made it that much more convincing.

It should be noted that this wasn’t the first time a Microsoft executive greeted attendees at an Apple conference. In 1997, then-Microsoft CEO Bill Gates was beamed in via satellite during an Apple conference to talk about Microsoft and Apple products working with one another. At the time, Apple was close to bankruptcy and Microsoft gave the company a much-needed $150 million investment that kept Apple on its feet. When Jobs first started talking about Apple and Microsoft working together during that event, the crowd grumbled and booed. Contrast that with the crowd’s reaction at Apple’s latest conference and you can see how the times have changed.

Meanwhile, under CEO Satya Nadella, Microsoft has been working on changing its image as a closed off tech business to one that wants to buddy up with others. His goal, after a year and a half on the job, is to make sure Microsoft’s products are compatible with those of other companies, even if those companies are rivals.

On Tuesday, Microsoft announced a partnership with both Dell and Hewlett-Packard (HPQ) to sell its Surface Pro tablets. Dell and HP, of course, have their own lines of tablets to sell.

As part of the new make-nice strategy under Nadella, Microsoft executives have also been busy appearing at conferences held by other technology companies. The message? Microsoft is a more cooperative player than under former CEO Steve Ballmer, who relished attacking rivals and criticizing their strategies. Nevermind that those attacks sometimes came back to haunt him.

Nadella is scheduled as a keynote speaker at Salesforce’s upcoming annual conference later this month. A few weeks ago, another Microsoft executive showed up at data center software giant VMware’s annual conference—a first time a Microsoft employee appeared on stage at a VMware event. Microsoft even shared the stage this summer at a conference put on by a fast-rising cloud startup called Docker.

The rate Microsoft is going with its 2015 tech conference tour, it will be more surprising if it doesn’t make a stop at any company’s event.

And while Microsoft and Apple may have had their past differences, there’s one thing they both should be able to agree on: tablet sales have been declining. Maybe the two together (along with Cisco, HP, and Dell) will help drum up some attention.

In this case, it might prove wise to make friends with your enemies.

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