What is Barnes & Noble announcing on October 26?

The retailer has invited reporters to its Union Square store on Tuesday, Oct. 26 for a "very special event". While Barnes & Noble wouldn't say any more (nor hide any teaser in the accompanying image, a la Apple) it's likely that the retailer will be announcing a new version of its Nook e-book reader that Barnes & Noble announced in October 2009 to compete with the Amazon Kindle.

The Nook e-reader last received an update in August, when Barnes & Noble trimmed the 3G functionality to create a cheaper wi-Fi-only Nook, at $149. B&N also rolled out version 1.4 of the Nook's software. (Amazon's cheapest Kindle is $139.)

But version 1.5 of the software, due out at the end of the month, will include faster page turning, syncing progress across all Nook devices, and password protection, among others.

So far, Amazon remains the leader in the e-book market, with a substantial lead in the number of titles, over 700,000 of them. But Barnes & Noble has differentiated itself with its colorful miniscreen and tolerable Web browser, and in-store experience.

It's probably fair to say that Barnes & Noble will offer at least the 1.5 version software upgrade, an increase in the number of available titles, and probably some sort of a unique in-store promotion - if not an entirely new Nook itself. Something like the ability to share books, or even some form of used-book option would be enthusiastically welcomed, but would probably run afoul of the publishers themselves.