There haven't been many good things about George W's almost 8 years in the White House, but his appointment of the wise and likeable Secretary of State was one of them. It was said at the time that Powell's dissatisfaction with the direction of the administration was the main reason that he left at the end of the first term.
Powell has led men into battle. He has dealt with foreign leaders at the highest level.
It is highly significant that he has today confirmed that he will be voting for Barack Obama.
It strikes me that the Democrats have lost Joe Lieberman to the McCain campaign - but Powell's endorsement is definitely a net gain for them.