With recent advances in communications, networking, and computer technologies, we have witnessed the emergence of large-scale user-centered web 2.0 applications that facilitate interactive information sharing and user collaboration via Internet – for example, blogs; wikis; media-sharing websites such as Napster, Flickr, and YouTube; social networking services such as Facebook, LinkedIn, and Twitter; and many others. Different from traditional web applications that allow only passive information viewing, these web 2.0 sites offer a platform for users to actively participate in and contribute to the content/service provided. The resulting trend toward social learning and networking creates a technological revolution for industries, and brings new experience to users.