At the FPD International 2010 trade show in Tokyo Tuesday, Chinese company Hanvon Technology is set to unveil the first full-color tablet using e-ink technology.

The e-ink tablet has a 9.68-inch color touchscreen with built-in Wi-Fi and 3G connectivity. It will be available for $440 in China this March — about $150 less than the cost of a 16GB, Wi-Fi-only iPad in China.

With a 78% share of the market, Hanvon is the most popular maker of e-readers in China.

Black-and-white e-ink is currently used in the displays of 90% of e-readers, such as Amazon’s Kindle and Barnes & Nobles’s Nook, according to The New York Times.

After the success of Apple’s iPad as an e-reading device and Barnes & Nobles’s recent announcement that the second-generation Nook would use a color LCD screen (rather than black-and-white e-ink), it seemed the days of colorless e-ink devices might be numbered. The addition of color could make e-readers more exciting for consumers who dislike the relatively short battery lives and glare of tablets with LCD displays.

Still, the new e-ink displays, which are produced by laying a color filter over standard black-and-white e-ink screens, are neither as vivid nor sharp as their LCD counterparts — The New York Times likened them to “faded color photograph[s]” — nor can they handle full-motion video.

Neither Amazon nor Sony have confirmed that e-readers with color e-ink are in the works.

“On a list of things that people want in e-readers, color always comes up,” Steve Haber, president of Sony’s digital reading business division, told The New York Times. “There’s no question that color is extremely logical. But it has to be vibrant color. We’re not willing to give up the true black-and-white reading experience,” he said.

Continuing with a very source agnostic digital book strategy, Barnes & Noble has announced it will soon be offering an e-reader app for the Apple iPad.

The app will be designed specifically for the iPad’s tablet form factor, and will join B&N’s existing e-reader app family already available for Mac, PC, iPhone , iPod touch, and BlackBerry.

In other words, although the company is selling its own Nook e-reader device, it doesn’t want to lock potential book customers into a single platform or device. The company saysthat the goal is “providing consumers any book, anytime, anywhere.”

Like the other existing apps, the iPad app will give users access to the Barnes & Noble e-bookstore with more than one million e-books, magazines and newspapers, plus access of course to its existing digital library. The company expects to officially launch the app around the same time the iPad will be available, which should be April 3 if the existing rumor has any truth to it.

As publishers continue to flock to the iPad, what’s your current take on the e-reader versus tablet war that’s brewing? Can the two form factors coexist, or will tablets like the iPad steal the thunder from e-readers?