Environmental Protection Agency (EPA) Administrator Lisa Jackson today announced her resignation. She is the second member of the Obama Cabinet to do so; Secretary of State Hillary Clinton was the first. No replacement has been mentioned as yet, but EPA Deputy Administrator Robert Perciasepe will be the agency's temporary head.Jackson's decision to step down coincides with an emerging controversy over her alias e-mail account under the name Richard Windsor -- her dog is named Richard and her former home was in East Windsor Township, New Jersey. EPA has defended the use of the account. It is not an unusual practice for high-level government officials to have personal e-mail accounts because their standard accounts can be accessed publicall...