Hillary is positioning herself to be VP in 2012, so she does this favor for Obama.... but I also think she is simultaneously positioning herself to be the Presidential nominee in 2012, should Obama tank so badly in the polls (which may be happening) that he cannot run.
This is why Hillary must be seen as a raging success as Secretary of State. When she started the 'Smart Power' Tour last Spring by visiting Asia... she hardly had arrived home before N.Korea started firing missles into the Sea. Smart Power works again!. That, and numerous other gaffs, along with numerous negative stories about her being marginalized by the Obama Administration led to a 'broken arm' that took her off the hotseat long enough to restudy positions with a few allnighters and opportunity to 're-do' and 're-make' herself. How convenient. (insert smirk here!)
Afterwards, she was able to 're-emerge' as the Marxist press revealed it to us, and now has a stronger and clearer (and more Presidential) tone.
That broken arm couldn't have come at a better time! eh? These people play us so well that all Americans should have a 'right' to free popcorn.
Hilary's actual performance in her job as SOS is irrelevant. If she chooses to run in seven years, or sooner if Obama becomes untenable to the the Dems (unlikely), then she will be carried to victory much the same way as Obama was last year. And, just like his inexperience wasn't a problem for the press, Hilary's poor performance experience won't be either.