Barnes & Noble took a shot at archrival Amazon.com on Wednesday, unveiling its own lighter and thinner hi-definition tablets that can accommodate multiple users in a bid to win a bigger share of the exploding tablet market. The largest U.S. bookstore chain introduced the new devices with price tags ranging from $199 for a 7-inch Nook HD tablet with 8 gigabytes of memory, to $299 for a 9-inch Nook HD+ tablet, similar in size to Apple Inc’s market-leading iPad, with 32 GB of memory. IPad prices are roughly twice as high for similar devices. Read the full story at Reuters.