The Ross Perot Foundation's copy of the Magna Carta, dated 1297, sold tonight at Sotheby's for $21.3 million, barely hitting the presale estimates of $20-30 million.
AFP reports that the document was "picked up by a telephone bidder."
[Slightly later: Reuters adds that the buyer was private equity firm founder David Rubenstein, who "plans to keep it where it has been on display at the National Archives and Records Administration in Washington." This is excellent news, I'm very glad to hear that the Magna Carta will be back at NARA very soon.]
[Update: See this post for more quotes and updates, including a revision of the first AFP report that the winner bid by telephone. Mr. Rubenstein was in the room.]