Why do you think WinRT doesn't have digital ink capability? It's something built into all Windows versions since windows xp tablet edition.
There are two variants, the Surface, and the Surface Pro. The 'normal' Surface is launching with Windows 8, and is powered by a Tegra 3 ARM processor. It does not have digital ink capability. The Surface Pro, launching a few months behind the Surface, has a ULV Core i5 processor, and the Surface Pro does have digital ink capability (but only on the Surface Pro). The Surface Pro hasn't had its pricing revealed, but it's priced in-line with current ultrabook pricing. A price point of $999 is very likely.
The surface pro does come with a pen, but that doesn't mean you couldn't get the pen for the Surface.