Release 20120510a of the Global Soil Respiration Database. This is a duplicate of the data currently available at http://code.google.com/p/srdb/downloads/list.
For more information on the database itself, see Bond-Lamberty and Thomson (2010), A global database of soil respiration data, Biogeosciences 7:1915-1926, doi:10.5194/bg-7-1915-2010.