Christopher Caen (probably a descendant of Herb Caen?) writes about the same possibility in the San Francisco Examiner:
Many local senior Democrats are smiling to themselves about the whole Harriet Miers debacle. And the reason is they saw it coming three weeks ago. The reality is I had several conversations with people in the California Democratic Party and the consensus was that good old Harriet was there to take one for the team. The reasoning was that the Democrats were never going to give the White House two confirmations in a row, so cannon fodder had to be provided. And if it was
someone who could infuriate the conservatives enough to get them back behind Bush on the next appointee, then even better. No sitting judge or elected official would take that bullet, but there is no collateral damage for Harriet, who just goes back to her job as if nothing ever happened. It never was a debacle, and now we will find out who they really want in that seat. But as articles across the nation leapt out of the pages of the national newspapers and bashed the Bushies for their “mistake,” it’s good to know that our local team wasn’t so easily fooled.
I don't think Bush is playing chess looking that many moves ahead, but it's an interesting theory.
Similar, though less Machiavellian, thoughts at Don Surber.