Dick Cheney's approval rating is already in the teens, so you could already say the presidency is held in its lowest repute ever. But the latest LA Times polling also has Bush down to a 23 percent favorable rating, his lowest ever.
This number was compiled before more deaths in Iraq. Before additional revelations about corruption in the Justice Department. Before continued declines in the market and the dollar. Etc.
(This poll also shows Obama with a wide lead over McCain. I'm tamping down enthusiasm on this score, having been down the good-poll road before, with Kerry, through election-day exit polls, and with Gore, who won but lost. But really: How could you vote for someone who endorses just about everything Bush stands for?)
UPDATE: In San Francisco, a movement is afoot (yuk yuk) to name a sewage plant after George W.