Barack Obama had a formidable online presence during his quest for the White House, and he is once again turning to the Internet to communicate with the American public as president-elect. Within 24 hours of last week’s historic vote, his transition team rolled out change.gov, a Web site that promises to be “your source for the latest news, events and announcements so that you can follow the setting up of the Obama administration.” The site is still a little thin on content, but there’s a blog, a newsroom and a countdown to the January 20 inauguration