It's been a big month for the handheld ultramobile PC, or UMPC. We reviewed not only the clamshell-like Vulcan FlipStart, we also got our hands on the sleek and sexy OQO model 02. Both these pocket-sized systems run full versions of Windows (either Vista or XP), and fall somewhere on the gadget spectrum between an ultraportable laptop and a PDA-like smartphone. The same could be said of two other second-generation UMPCs we've looked at recently, the Sony VAIO UX390 and the Asus R2H.

Sony VAIO UX390

Of course, the story is rarely as simple as that, and the much-hyped UMPC platform mostly fails to live up the industry's (perhaps unrealistic) expectations. Thanks to clunky interfaces, high prices, and poor battery life, we have yet to see one that we'd consider useful in day to day real-world situations. My colleague David Carnoy says much the same thing in his column, provocatively titled, "Why you'll never buy an ultramobile PC."

The UMPC is still largely an idea in search of a purpose, leaving us with a series of concept pieces that look nice in a showroom, or as executive toys, but other than that, we're hard-pressed to figure out who the target audience is.

Each model we've reviewed has positive aspects as well as one or more fatal flaws. If someone could magically pull together all of the best parts of the different UMPCs on the market, add a decent battery, and also not make us feel like these delicate devices will fall apart if we look at them funny -- we might be on to something.

Sony's VAIO UX390 is an excellent example. The slide-up keyboard is handy, and we liked the multiple input options (keyboard, touch screen, and pointing stick), as well as the solid state hard drive. The device as a whole, however, is expensive, offers limited battery life and is a little too big for easy toting.

OQO model 02

The OQO model 02, has a great slim form factor and a large (for a handheld device) bright screen. Its keyboard is one of the better thumb keyboards around, but a pointing stick is your only mousing option. The battery life is very short and actual performance is somewhat sluggish compared to other UMPCs, making this a device that has the look down, but needs some work in the other categories. Even worse, the Sprint and Verizon WWAN-enabled versions have just been further delayed.

The Vulcan FlipStart, the long-delayed UMPC from a company started by Microsoft co-founder Paul Allen, takes a different approach. This device looks almost like a shrunken laptop. The blue clamshell design offers more protection for the screen and keyboard than the other models, but as a whole, it's a pretty big brick to lug around. It did however have one of our favorite features--a tiny 1.5-inch touchpad, which turned out to be the easiest way to manipulate the mouse pointer on any of these UMPCs.

Vulcan FlipStart E-1001S

In truth, all these machines are fine for Web surfing, which is what most people seem to use them for. From personal experience, working on a Word document (perhaps writing a product review) is a chore on any of these keyboards, but possible in a pinch.

While we await the release of the newest much-hyped ultraportable PCs--the Samsung Q1 Ultra, and the HTC Shift--we'd like to challenge system makers to combine the OQO's slim design with the FlipStart's touchpad and the VAIO UX390's solid state hard drive, plus a decent battery and a dual-core processor. Too much to ask? Of course it is, but we can dream, can't we?

See all these models side by side in our review roundup.