Matt Flynn is a Seahawk. 3 Years, $10m guaranteed. No draft picks were lost so it doesn't hamstring the franchise. He's unproven yes, but one of the offensive coaches knows him well from his time in Green Bay.
This situation is eerily similar to Homegrown picking up Hasselbeck from QB years ago. It's worth a shot.
Now if Manning goes to Tenn and Alex Smith gives SF the finger and goes to Miami, the Seahawks could actually have a shot to win the division. But i think Peyton is going to SF.