Promises, promises. When a new mobile phone appears on the market, or a new wireless standard emerges, the pundits and prognosticators chime in about all the game-changing possibilities.

WiMax will change the world! Apple's iPhone is the second coming of portable gadgets!

Yet, in the daily grind of computing, we just need to get our jobs done. We'll believe the promise of a new technology if it really does solve a nagging problem.

Consider this the companion piece to my earlier article, "10 broken technology ideas -- and how to fix them": six promising technologies and how they can actually deliver on the promise.

1. Light-as-air laptops

I mentioned in the broken-technology writeup how ultramobile PCs and mobile internet devices aren't nearly as useful as a good smart phone.

Stepping up a bit in size to notebook PCs, we've come a long way from models such as the massive Toshiba Protege from a few years ago -- the one with a 17-inch display. (It was touted as a "desktop replacement," which even sounds heavy.)

And even the popular Dell Latitude models from not so long ago were heavy enough -- at about five or six pounds -- that they weren't exceptionally mobile.

But smaller, more recent offerings such as the ultraportable Asus EEE aren't getting it right either. Sure, it's light, but it's not packed with many of the features we've come to expect on our portable computers.

But the new MacBook Air and the ThinkPad X300 really are game-changing, even though many reviews of the MacBook Air haven't been all that positive.

A 1.4 kilo laptop with a big screen is really the ultimate goal, and both Apple and Lenovo Group achieved it. (I also like the Sony Vaio SZ, even though it weighs more and the "profile" measures 1 inch) So, what's so promising? As laptops get lighter, you'll be more likely to grab one and go -- at home, at work and anywhere.

Soon, more light-as-a-feather laptops packed with features will finally get it completely right, which means they won't stay on the desktop for very long -- and the desktop PC might not exist for long, either.