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Sherlock Holmes in Orbit? It's a collection of short stories and I can't seem to find a summary of what each story is about, but these links might help...
http://www.amazon.com/Sherlock-Holmes-Orbit-Mike-Resnick/dp/0886776368
http://www.sfwriter.com/tcsherlo.htm
http://en.wikipedia.org/wiki/List_of_authors_of_new_Sherlock_Holmes_stories
IIRC, it was Sherlock Holmes, WITH ALIENS!! - only here, Holmes was the personal assassin of Queen Epiphany I. Any clues?...