According to The Verge and the Naver Cafe online forum Nokia was set to release a Windows RT tablet on Q4 2013-- a device the company has allegedly cancelled in favour of a Windows 8.1 version.
The Korean forum shows what looks like a 10-inch tablet complete with what the poster says is a magnetic connector similar to those found in Apple MacBooks and Microsoft's own Surface.
The prototype supposedly carries an Nvidia Tegra 3 processor, USB and HDMI ports, SIM slot (with 4G/LTE support) and 3.5mm headphone jack. It also features "Nvidia P1001" as a product number-- perhaps proof of the device's status as a prototype.