A major theme of Windows 10 is the consistent experience provided across various devices and screen sizes, from phones to tablets to full-blown desktop PCs. Microsoft even wants to make some of the Windows 10 universe available to those who aren't using Windows Mobile (that is to say, most of us). To make this possible, Win10 will include a Phone Companion app to help Android and iOS users set up the right Microsoft cloud services on their devices. Microsoft will also release a version of its Cortana personal assistant for those operating systems.
Based on the screenshots and video Microsoft has provided, it looks like the Phone Companion app will basically walk owners of non-Microsoft phones through the process of setting up apps like OneDrive, Office, and Xbox Music on their respective operating systems.
Through the magical power of the cloud, pictures taken on iOS or Android will then be automatically uploaded to OneDrive, making them accessible through Windows 10's Photos app. Music stored in OneDrive will be available for playback on any device with the Xbox Music app installed. Office apps will pick up files stored in OneDrive, and notes made through Cortana and OneNote will automatically sync across devices, as well.
Speaking of Cortana, a standalone version of Microsoft's digital assistant will be coming to iOS and Android, too. Though it won't be as deeply integrated into these operating systems as it is in Windows Mobile, Cortana will still be able to provide reminders, take notes, and answer questions about subjects like the weather. Folks without Windows Mobile devices won't be able to invoke the assistant by saying "Hey Cortana" or toggle settings with voice commands, though.