The expanded edition of Russell T. Davies' The Writers Tale comes out soon, covering his work up to David Tennant's final Doctor Who story. And reportedly, the new version tells of the Torchwood musical that never was.
According to the Doctor Who News Page, ABBA members Benny Anderson and Bjorn Ulvaeus were huge fans of Torchwood. And they were part of a group that approached Davies about doing a musical version of Torchwood — I'm not sure if this means a musical episode of the show, a stage musical version, or something else. In any case, the Torchwood musical never got past the concept stage, which anyone who's heard John Barrowman sing will be sad about. [Thanks to Finsbury for the heads up!]