Definitely unreleased. Not part of any kit, never sold in shops. Actually, never seen it before, not even friends who worked at the local GW store at the time had it. So not a staff gift or the like.
Seems genuine GW though. GW seems to have made a fair number of new Empire and Halfling (and Dwarf?) sculpts around 2010, but only a few were produced & sold.
-Z