Google introduced in its webstore the Google Books Android app , an app available to the US market only for the moment. There are rumors that Google will extend the Android Marketplace offer from e-books to movies and music.  Two months ago Google launched its e-Bookstore and ever since has been making efforts to improve the service and secure its place in the market dominated by Amazon and Apple.

It hasn’t been that long since Amazon publicized its Kindle updates, introducing public notes, real page numbers and social sharing. The update enriches the newspaper and magazine reading experience by introducing subscriptions for the Kindle device. The new layout for newspapers and magazines is formatted to allow users to scan news faster and decide on which title is more interesting.

Subscriptions have been a sensitive matter in online digital content in the past week or so. Apple is notorious for its straightforwardness in dealing with subscription issues and maintaining its 30% share for each a new subscriber to the app, and giving competitors such as Google and Barnes & Noble a competitive advantage.

On their earnings call, Barnes & Noble announced their holding of 25 percent of the US market, an estimate that might appear a bit exaggerated, but explained by Barnes & Noble in terms of sales: the company says it’s selling twice as many ebooks as physical books in any format from its online store. In 2010, Barnes & Noble claimed it held 20 percent of the US market, whereas Amazon claimed a 70-80 percent market share.

Barnes & Noble is keeping pace with the latest e-reader releases in order to keep the high sales figures and announced that later this spring will launch a new version of its Nook for Android 3.0 Honeycomb, offering enhanced graphics, a grid view, and will optimize the reading and shopping experiences for larger tablet displays.