Starting this thread for Windows RT as this will be Microsoft's Tablet OS to challenge the iPad.
Expected for release around October and I believe we'll see a lot of these tablets once they're available.
10.6-inch Microsoft Surface tablets announced, powered by Windows 8 | The Verge
Microsoft Surface with Windows RT runs an Nvidia Tegra processor | The VergeSurface powered by an ARM chipset and Windows RT. The Windows RT version is just 9.3mm thin, weighs 1.5lbs, includes a built-in kickstand, and is the first PC with a vapor-deposited (PVD) magnesium case, according to Microsoft. It will ship in 32GB or 64GB versions, complete with a 10.6-inch ClearType HD display (of unknown resolution)
Windows RT's biggest selling point... Office 2013 RT!
Office 2013 RT for Windows RT tablets will ship as Preview, lack macros and other features | The Verge
Lenovo, Dell, and Samsung Windows RT tablets and laptops confirmed | The VergeTo optimize for Windows RT, Microsoft has made the decision to remove a number of features from its Office 2013 RT release to ensure battery life and reliability are not impacted on tablet devices. Macros, third-party add-ins, and VBA support will all be dropped from the Office 2013 RT edition, and one source says a "small number" of other features have also been removed. We'll have to wait for Microsoft to detail all of its changes, but although a spokesperson says the company has "not finalized any packaging," we understand that Microsoft Office Home & Student 2013 RT Preview will come preinstalled on all Windows RT devices.
Windows RT tablets could start at $300, according to Lenovo executive | The Verge