It's not very often that one of the original 60 stories from the Sherlock Holmes canon goes on the market. Which is why news of the June 21 auction of the manuscript of "The Three Gables" is likely to attract quite a bit of attention.
The aucton is being held at Sotheby's in New York (click the link for limited details) on June 21 at 10:00 a.m. Previews are available from June 15 - 20, 2007 and a catalogue is available for purchase. The manuscript, once owned by the Marquis of Donegall and then Walter Pond, BSI, is expected to fetch approximately $350,000.
If you're curious about these sorts of things, a great resource with lots of detailed information about Conan Doyle's Sherlock Holmes and other manuscripts, please take a moment to bookmark Randall Stock's site. Randall acts as the central clearinghouse of background and whereabouts of the manuscripts, aided and abetted by many noted collectors.