UPDATE 6/7/15: Microsoft recently completed its purchase of N-Trig pen technology and is now hosting the Wintab driver. For more details, read the story here: http://surfaceproartist.com/blog/2015/6/2/new-download-link-for-n-trig-wintab-driver
N-Trig has just posted R16 of its Wintab drivers for the Surface Pro 3 and other devices utilizing their digitizer technology.
You can find both 32-bit and 64-bit versions here: http://www.n-trig.com/Content.aspx?Page=wintab. (As of this writing, searching for drivers through the Downloads & Drivers tab yields the older R14 version.)
I haven't had a chance to download or install these drivers, but once I do, I'll begin updating the "What Runs, What Doesn't on the Surface Pro 3" feature.
According to N-Trig's Ronen Bartal, the company confirmed that the following software is compatible with these drivers:
Anime Studio Debut 9.5 Version 9.5 build 9768
Crayola PhotoFx studio 1 Version 126.96.36.199, 188.8.131.52
Flash Professional CC Version 184.108.40.206
Adobe Flash Professional CS6 Version CS6
Corel Painter Version 220.127.116.113
MyPaint Version 1.0.0
Mischief Version 1.12
Zbrush Version 4R6
Adobe DreamWeaverCS6 Version CS6
Adobe Photoshop element 12 Version 12.0.20130925
Krita Version 2.8.3
Substance Painter Version 0.5.0
Adobe Photoshop CC and earlier versions are noticeably absent from this list, but that may be because that software has functioned correctly with N-Trig's drivers for some time.
Bartal also notes that other software that correctly adheres to the Wintab 1.4 specification should also work, although apparently many applications do not. For more details on Wintab and its history, visit http://www.wacomeng.com/windows/index.html.
This release marks a major milestone for N-Trig and users of its products as the drivers significantly close the compatibility gap with competitor Wacom.