This is a 1:1 scale replica of the sonic screwdriver that was used by Professor River Song in the fourth season episodes "Silence in the Library" and "Forest of the Dead" and appears to be a heavilly modified, even Steampunk looking version of the sonic screwdriver utilized by the 10th Doctor (David Tennant). Featuring a fixed forward facing section which lights up and emits and light when buttons are pressed, it produces two different sonic screwdriver sounds from the BBC Radiophonic Workshop - as well as displaying a light in its hidden compartment - shown here revealed.
(May 22nd 2011) Off-subject, I have a thought on recent comments made in the dialogue of the Fifth Season - more so in regards to the message Rory was given for the Doctor which was "The only water in the forest is the River" - could this mean that River Song is in fact related to Amy Pond (water) and that she is in The Library (forest) where you may recall River sacrified her life, placing what was left of her personality into the sonic shown here.
Legal: This image was created using a toy and is shown here for the purposes of education and artistic appreciation only and the image should be considered a review of a Doctor Who related product. The TARDIS and all associated information related to the series “Doctor Who” remains the intellectual property of the British Broadcasting Corporation.