Although not a straightforward solution - not sure it will work, but hoping - there's the LEAP Motion Controller. It looks fantastic!
They say that it doesn't directly support tablets or smartphones; but, with at least some sort of manual calibration, it can easily be set to work on inclined planes/displays (even horizontal ones) with custom sizes, disregarding the main monitors's size/distance/inclination.
In other words, if you have a high-res tablet (like the new non-mini iPads, although that might be a bit small for graphic design) you can use the LEAP as the pointing/stylus with pressure/speed/rotation/etc capabilities and the tablet as the display. Then the tablet only has to display whatever is on the PC's display in real time, but I don't of know any apps for that.
Of course, any good display that can be inclined low enough (or maybe any display; if you use aisles; I draw on the table with my head down :/ ) would work perfectly with the LEAP.
I'm already set on that one (preorder, yay!) and will let you know as soon as I can work with it. Though I don't have any tablets to try it on. If you find android/iOS apps that can show the PC's display video stream on a tablet, and if you have a LEAP, give it a try and let us know how it goes.
~~ May 2013
According to a survey posted by Wacom sometime in April, they are working on a Design Tablet with either Asus or Samsung (both were mentioned in the survey). There was no info on the OS and the maximum size mentioned was 7 inches.
*So realistically, the only options seem to be the Bamboo tablets from Wacom.
*For $99, I heard that Wacom's Bamboo Capture is a really good deal.
See this for a bit on what's available.
-I've also found this but cannot comment on it, recommend it or otherwise.
There's also the Inkling which is said to work with tablets other than the iPad.
All in all, it's a no for the original question. Until Wacom does something about their promised tablet(s), we're out of luck. Any software available for Android today to provide touch input to PC's would lack precision even if the tablet was able in hardware. The options marked with the asterisk (*) are available in the market today while those with the hyphen (-) look very promising on paper.
Material ~~ August 2012