I was in the downtown library yesterday with my MacBook (which doesn’t get out much anymore, now that I have an iPod Touch).

Some dude I’d never met before came up and started talking to me. At the downtown library, this happens rather often. But this guy wasn’t trying to sell me a bus pass or tell me a long story that would start by asking for directions and end by asking for money.

He just wanted to alert me to something he’d seen on an Apple rumors site. It was another variant of the long-rumored Apple tablet device. “It’s like a MacBook without the keyboard, or a big iPod Touch. It looks great!”

Now I’ve seen one of these new rumor articles. And I must say I like the specs the article mentions. This is almost exactly the device I’d dreamed of earlier this year, when I speculated that the future of the online written word (including journalism) lay in .pdf documents formatted for tablets and netbooks.

(My caveat: While I’m intrigued by the concept of an Apple tablet as a full-page-size iPod Touch, I suspect many users will also want to use it for more traditional home-computer functions, including functions at which the iPhone OS and its available apps are still insufficient.)

Meanwhile, closer to home, other tech rumor sites are spreading an internal Microsoft video, demonstrating the features of what might be that company’s next-gen tablet computer concept, code named “Courier.” Like the rumored Apple device, the rumored MS device wouldn’t run a regular home-computer operating system. Instead, it would operate its own integrated suite of apps, based on the metaphor of an “infinite journal” where the user could clip and paste anything from/to anywhere.

The warning here is that MS has whole teams of “futurists” and conceptual designers working full-time on the personal-tech version of “concept cars”—items that, in their initial iterations, will never see a sales shelf, but which are used to work out ideas that may eventually find their way into real products. Courier might be one of these.