If there is any doubt in your mind who is No. 2 in the Obama administration, watch the body language of Obama's December 1, 2008 press conference announcing the national security team. While Joe Biden finally was allowed to appear in public, the body language was all Hillary.
Watch the video carefully, at 43:45 on the clip. As the press conference was ending, Obama moved towards Hillary, put his hand on her arm, and the two walked off the stage arm-in-arm. Two thoughts.
First, despite his historic election, Obama seems somewhat intimidated in the presence of Hillary. She dominated the stage, and Obama's act of coming over to her in an endearing manner was deferential. The weight of Hillary's personality, and all the history she brings with her, will crowd out others.
Second, didn't Obama get sexual harassment training? A male boss simply doesn't put his hands on a female subordinate, even if she consents. At least Obama didn't call her sweetie.