With all the announcements coming out of //Build, I'm pretty jazzed about what's coming in Windows 10. That doesn't stop me from wishing there were one or two other scenarios Microsoft would get to... and at this point, I'll have to hope to see them in something after Windows 10.
"App-V-Motion" running apps, migrating them across devices.
Enable an app running on the phone or tablet or laptop or desktop to seamlessly transition from device to device.
Imagine it's getting late in the day... you have a long running process on your desktop that you need to babysit. Poor timing, sure, but it happens far too often. Now, rather than being tethered to your desk, you can transition the process to a mobile device, and simply take it with you. Perhaps it'll take longer to complete on the mobile device, so when you get home, you hand it back off to bigger iron.
or, my other favorite scenario... you're watching your favorite movie, but it's time to roll.... so you hand off the movie player app to your phone, and keep watching while you're on the go, without missing a beat.
With cloud configuration & storage, this scenario is getting more and more feasible, but given where I'm seeing Windows 10, now, this could potentially be a 10.1 or 10.2 feature.