[Update: The AP is reporting that the price paid for the Lincoln letter is "a record for a Lincoln manuscript, as well as for any presidential and American manuscript."]
The results from this morning's Presidential and Other American Manuscripts sale at Sotheby's New York are available here. As expected, the 1864 Lincoln letter responding to a childrens' petition calling on him to end slavery did particularly well: it sold for $3,401,000 with premium.
Other highlights: A Lincoln signature on one of four leaves disbound from an autograph album signed by dignitaries after the Gettysburg address sold for $937,000. This is the only known Lincoln signature from the day he delivered the Gettysburg Address. Only one other item made more than $100,000: an 1863 Lincoln letter to Asst. Secretary of War Peter Watson ($121,000).
The surprise of the sale (to me, at least) was the next-highest item: a 1924 Calvin Coolidge letter written to a Boston friend about his views on presidential duties. That beat its $15-20K estimate by a fair margin, selling for $85,000.
A Thomas Jefferson letter from 1790, expected to fetch $200,000-300,000, failed to sell.