Fannie and Freddie at Risk?

Standard and Poors is warning that the GSEs are facing increasing risks as the housing crisis deepens, and so they might at some future time have to downgrade them.

Being the 2nd and 3rd largest borrowers in the world, they are firmly in the "too big to fail" camp, the regulators have reduced the reserve capital requirements for the GSEs (also here), and Congress making noise about increasing their lending limits^*, I'm not particularly confident in Fannie Mae and Freddie Mac remaining particularly solvent.

^*Shoot me now, I'm agreeing with some puke economist from the Heritage Foundation.