Get LoggedIn user from icefaces backing bean....
Code:
String remoteUserId = (String)((Map)FacesContext.getCurrentInstance().getExternalContext().getRequestMap().get("javax.portlet.userinfo")).get("liferay.user.id");
User user = UserServiceUtil.getUserById(Long.parseLong(remoteUserId));
String userName = user.getScreenName();
System.out.println("LoggedIn user: "+userName );