With the tablet market flooded by countless options from many companies, many are calling the tablet the future of mobile computing. But a Microsoft executive is not so convinced.

Speaking at a lunch in Sydney, Australia, Microsoft's chief research and strategy officer. Craig Mundie, said the future of the tablet is an uncertain one. Mobile is something that you want to use while you're moving, and portable is something that you move and then use. These are going to bump into one another a little bit and so today you can see tablets and pads and other things that are starting to live in the space in between, Mundie said. Personally, I don't know whether I believe that space will be a persistent one or not.

Mundie's comments come shortly after nearly all major device manufacturers have announced entries in the tablet race. In addition to Apple, Research in Motion, Hewlett-Packard, and Motorola, many others have staked out claims in the tablet market, which is rapidly expanding at the expense of netbooks and PCs.

Microsoft isn't expected to take a role in the tablet market until late 2012, when the company is expected to launch its own tablet operating system.

Mundie also finds himself in opposition to Apple CEO Steve Jobs, who not only sees tablets as the future of computing, but post-PC devices in their own right.

It's in Apple's DNA that technology alone is not enough. It's technology married with liberal arts and humanities that yields us the result that makes our heart sing. And nowhere is that more true than in these post-PC devices. And a lot of folks in this tablet market are rushing in and looking at this as the next PC, Jobs said during the iPad announcement.

And there may be something to Jobs's argument. Research firm Gartner expects tablet sales to top 19 million this year, and 54 million in 2011. Projections for 2014 point to sales surpassing 200 million units, according to Gartner's analysis.