Moore’s law is at it again, and the latest sacred cow to be slaughtered by this force of nature is the notion that a laptop need weigh about 8 pounds and do everything that a desktop can do.

OK, so the notion of an ultra-portable PC isn’t exactly new–hardware manufacturers have been chipping away at it for decades, with mixed success. In an era when smart phones can read word documents and even my Nintendo DS can browse the web, do we really need a teeny-tiny computer-ish thing that’s missing some critical features but not others?

The answer is a resounding yes, and has been since the TRS-80 Model 100 became one of the best selling PCs of its era.

This now-forgotten device, a favorite with journalists, was arguably the world’s first ultra mobile (it came out in 1983). It ran for 20 hours on 4 AA batteries, had a full keyboard and modem, and included a word processor, date book and a terminal–and, 20 years later, is still in use today.

The Palm Foleo

Enter Jeff Hawkins’ (the man who invented the Palm) Foleo. There are other subnotebooks of similar dimensions, such as Dell’s X1, which also weighs 2.5 pounds but has a bigger screen — 12.5 inches vs. the Foleo’s 10.

But the X1 cost $1500 and the Foleo costs $500. How’s that possible?

The real innovation here is stripping out Windows, which not only saves the manufacturer a couple hundred in licensing fees to Redmond, but also allows the laptop to be speedy despite much more modest specs, which include a slower processor and a flash-based rather than spinning-platter hard drive.

Despite some truly cool features — including instant-on and instant application switching — the Foleo has a number of drawbacks, most of which come down to marketing issues — seems that if Palm would just admit it’s a laptop and start equipping it as such (software wise) rather than insisting that it’s a “smart phone companion” folks might see it in a different light (I for one might buy it anyway just as soon as the linux hackers have a chance to turn it into a more versatile machine).

The Foleo’s heart is in the right place–unfortunately for Palm, the folks who might actually deliver on Hawkins’ dream are all the other companies who are going to be coming out with ridiculously cheap ultra-portable, linux-powered laptops in the coming year. The contenders:

The Asus EeePC

The fabulous laptop with a craptacular name, the Asus EeePC is my pick for runaway sales and market dominance, IF the interface and bundled software doesn’t suck. (That’s a big if.)

For the same price as an X-box ($200 or $300) you get a fully-functioning laptop (Intel 900 MHz Pentium M, 7 or 10 in. display, 512 MB Ram and 4-16 GB flash hard drive) that weighs 2 pounds. No fuss, no muss - that’s it - the computer for the rest of us, or at least anyone who wants portability with the least amount of hassle possible. When someone finally succeeds at creating the iPod of go anywhere, do-anything PCs that fulfills all the basic functions we need (web browsing, e-mail, etc.) it will look like this. Expect to see the first models some time this year.

Via NanoBook

Also weighing in at 2 pounds, the Nanobook has the advantage of running Windows (if you can call that an advantage on an under-powered portable that will probably strain under the bloated code-base). It’s even more than the Foleo, however, at $600. Great if you’re married to Windows — and science knows most of us are. No reason you couldn’t strip out Vista and replace it with Ubuntu, though…

Anyone else have a favorite ultra-portable, or reasons why they would or wouldn’t want to get their hands on one? (Anyone else miffed that Apple hasn’t entered this field yet?)

Update: How could I forget, the grand-daddy of them all, The One Laptop Per Child project

Started by MIT in order to deliver an inexpensive, tough laptop to kids in the developing world, will be selling to consumers, after all. This could be the most innovative machine on this list, given its unique features.