One of the very best cabinet picks that President-elect Obama has made got a bit lost in yesterday's "team of rivals" coverage.  Arizona Governor Janet Napolitano to head the Department of Homeland Security is a brilliant pick. She'll bring a combination of smarts, no-nonsense pragmatism, and moral clarity to an agency - and set of issues - much in need of all three. No one knows better than she - as an extremely popular and effective border state Governor - what it will take to move forward with serious immigration reform.  And, with respect to the Department's overall agenda, she's got the toughness to walk that fine between keeping us safe while adhering to fundamental constitutional values.