This is a short story in which Bear makes Doc Holliday (_the_ Doc Holliday of the Wyatt Earp and gunfight at the OK Corral fame) find himself guiding some mysterious outsiders interested in a rusting wreck that one of the group describes as a 'starship'. This was part of a collection I'd got from Amazon for something like 50p and, together with a short story by Charlie Stross, is by far the best of the book. Wild West SF! Alien starships! Gunfights! Time trav-ah, that might be a spoiler :) Enjoyed it enormously and now you can get it for free as Tor are giving away a compendium of their science-fiction short stories as part of their fifth anniversary celebration. You do have to register at their web-site, mind.