xThink's MathJournal application for TabletPC's (and PC's with a peripheral graphics tablet, like a Wacom tablet) will be ready for production release in about 3 or 4 weeks (i.e., the end of July) The price will be $198 USD. This information is preliminary and subject to last-minute change.
Folks who followed the early OpenRPN discussions on this forum may recall that MathJournal is an application that allows the user to handwrite a mathematical expression, in a paper-like environment, which is then recognized and solved. Systems of equations, and some symbolic math can also be solved. Graphs can be created, rescaled and resized fairly easily. Handwritten annotation and drawings are also permitted.
I'm not sure if this is the future of computing, but it certainly sets the bar at a new level...!