Facebooks $19-billion (14-billion-euro) takeover of smartphone messaging service WhatsApp staked the social networks place in dramatic fashion as a pivotal player in the mobile world. The US social networking giants 29-year-old founder Mark Zuckerberg snatched the limelight ahead of his debut as the star speaker on the opening day of the February 24-27 World Mobile Congress in Barcelona, Spain. Overshadowing even the hotly anticipated release of Samsungs new Galaxy S5 smartphone at the mobile fair, Facebooks cash-and-stock deal reflects a structural shift towards mobile by Internet and related technology industries. For Facebook, smartphones and tablets represent a fast-growing and crucial source of advertising revenue.