Ars Technica wrote:

The Mobile High-Definition Link (MHL) standard already lets you connect certain phones, tablets, and other devices to your TV using adapters that connect to the devices' micro-USB ports. But the consortium has just announced that an upgrade is coming: the new MHL 3.0 standard adds support for 4K displays. This will allow mobile devices that support the standard to output 3840x2160 (also known as 2160p) video at up to 30 frames per second, an upgrade from MHL 2.0's 1080p.

The updated standard can transmit data and video simultaneously, and a device connected via MHL can draw up to 10 watts of power to charge your device. Backward compatibility with MHL versions 1.x and 2.x, HDCP 2.2 DRM support, and 7.1 channel surround sound support are also part of the standard.

[...]

Gizmodo wrote:

Qualcomm builds chips for virtually every mobile device manufacturer you can name. 1920 x 1080 pixels (1080p) on five inch screens-which are popping up like crazy on new high-end phones) have 440 pixels per inch. You couldn't see those pixels if your eyeballs were pressed to the glass. So, I asked him what the point could possibly be. It's just a pointless manufacturer pissing contest, right?

Raj's answer was that sure, above 400 PPI or so, it's not really about how many pixels the screen itself can display, what's important is how many pixels the phone is capable of pushing, as in CPU and GPU horsepower. It's because of things like Miracast, where you can wirelessly push video and audio to your TV. If these upcoming phones with the superfast Snapdragon 800 processor can shoot 4K UHD video, wouldn't it be great if you could push that directly to your 4K UHD TV? Damn right it would. And there's certainly room to go well beyond 1080p on larger tablet screens.

Ars Technica wrote:

Of all the possible future of computing devices, one that seems so appealing-superficially, at least-is a single converged gadget that does it all. A pocketable thing that gives you computing and Internet connectivity when you're out and about, but it's equally capable of driving a big-screen monitor, mouse, and keyboard when you're sitting at a desk doing some work, watching streaming media, or playing a game on your TV.

This is, I would argue, the future that Microsoft is driving at. Microsoft has long maintained that tablets are PCs: that a computing device is a computing device, and that it should support many different kinds of input devices and applications. A device's role should be defined by how it's being used at any moment in time, rather than its role being an essential characteristic of the device.