Barack Obama was the second person to reach 10 million facebook likes, after Lady Gaga. Facebook for sure plays a distinctive role in online communications, and politicians in particular seem to be very fond of how facebook helps them connect, talk and get feedback. When politicians become part of someones daily news feed, they connect in ways that are yet to be determined as to how they can shape future relationships and influence voting behavior.
When people spend time in providing feedback, or channel political messages to friends, they need to be acknowledged for that. facebook provides an intimate online technology platform that drives interactions in being more personal. I can understand that engaging in dialogue can be time consuming, but politicians, in trying to help their constituents, need to get personal and provide useful information, just like other "facebook friends".
Last year nobody knew Lady Gaga, she did however passed the 10 million mark before Barack Obama. Social Media communications strategies for artists are totally different, but some core communications principles stay the same.
George W. Bush has not reached 10 million likes yet... he is however utilizing facabook to update people on his status, and recently spoke in his first inaugural address on facebook.