For Obama, it's merely icing on his already sweet victory cake. Richardson's endorsement will pull about as much weight with voters in the General as would A-Rod's or Jennifer Lopez's.
But for HRC, it's a consequential refutation by one of her own family members, a man who Bill Clinton essentially "made." If she cannot even secure the support of pols who owe their own success largely to the efforts of Clinton, Inc., how in the world is she supposed to gain support from those who owe her husband nothing?
Richardson's endorsement can best described as "rats deserting a sinking ship," smart rats, to be sure.
It helps Barack only by hurting Hillary.
[Note: One thing about HRC: this woman can sure take a pounding and remain upright. She's actually showing more character as an also-ran than she did as the front runner.]