No visible rust. I pried the clamp slit apart slightly and dribbled some Liquid Wrench in from the top. I can also get it into the seat tube through a bottle cage hole, so I'll do that and hang it upside down tonight. The seatpost is fluted, but the flutes are above the top of the seat tube so I'm assuming it isn't set in very deep.

It's a nice Dura-ace seatpost, but if it doesn't come loose soon it will get some force applied to it.