LinkedIn continues to grow in the U.S. where revenue was up 73% year-over-year in the most recent quarter, but it's also exploding internationally. Third-quarter revenue between 2011 and 2012 popped by 117% in Canada, Latin and South America; 89% in Europe, the Middle East and Africa; and 108% in the Asia Pacific Region. (Numbers courtesy of LinkedIn's most recent 10-Q filling). Mobile traffic as well as engagement also continues to grow exponentially. Skeptics question social Web companies about long-term sustainability. How can you ensure that you do not outlive your usefulness? Great question. And there's never a definitive answer. Investors need to look at factors such as how quickly a team can implement new solutions that actually do what they're supposed to do (content drives engagement; engagement leads to premium subscription revenue) and who's in charge. I'll take LinkedIn with Weiner at 42 years of age any day of the week. While its lofty multiple might hold it back, don't be surprised if another social player or social wannabe takes LinkedIn out. It would be a valuable complement to a wide-ranging swath of social or new media stables or upstarts. Follow @rocco_thestreet --Written by Rocco Pendola in Santa Monica, Calif.