WASHINGTON (Reuters) - So much for "Facebook fatigue." A survey released on Friday shows that people who have used the social networking site over a long period - since its founding in 2004, say - show no sign that they are tired of posting pictures, updating weekend plans or just relaying random thoughts. The Pew Research Center report, based on a U.S. phone survey, logs and data from November 2010, sheds light on Facebook's possible long-term popularity as the company founded by Mark Zuckerberg heads for a $5 billion initial public offering. ...