Earliest record I'm aware of was two limited-scope papers about rigging linear algebra systems onto GPUs in 2003: Krüger and Westermann out of TU Munich and Bol

Earliest record I'm aware of was two limited-scope papers about rigging linear algebra systems onto GPUs in 2003: Krüger and Westermann out of TU Munich and Bolz et. al. out of Caltech. Both were published in the same 22(3) issue of IEEE Transactions on Graphics. Followed by the BrookGPU stuff out of Stanford that kind of cobbled a stream processor API out of OpenGL1.3 or DX9 calls in 2004. Earliest practical would presumably be the first round of GPUs with programmable shaders in ~2005 with the ATI R520 (X1000) and the nVidia G70 (7800GTX). Coming up on a decade later, ATI/AMD will surely commit to a cogent programming solution soon...