J Allard, one of the key men behind the design of Xbox and Xbox 360, could be on the verge of leaving Microsoft following a dispute over the canning of his latest project, the Courier Tablet.

According to rumours, Allard has been on a sabbatical and may not return to MS after the company decided not to put the new device into production.

The Courier Tablet, behind which Allard was reportedly the driving force, is an almost iPad-like portable touch-screen tablet computer with two screens that fold out like a book. It looks brilliant (see a video of it in action below) and was due for a 2011 release, but was suddenly and unexpectedly canned last month.

This decision was apparently the topic of major disputes between Allard and CEO Steve Ballmer, with unnamed sources close to the firm reportedly telling ZDNet that Allard, while currently still an MS employee, is unlike to return from his sabbatical.

MS has refused to comment on "rumour or speculation", but one source told ZDNet: "[Allard] was one of the few there that really was willing to think outside the box and has people working on top secret projects off the main campus....He was regarded as being a bit (Apple CEO Steve) Jobs like in that he understood the importance of design, not just function. Hence if he departs Microsoft would lose an important design advocate and innovator."