The GM107 hardware, a.k.a. the GeForce GTX 750 series, now has the basic compute support via this commit. Samuel noted in the commit message, "Fortunately, compute support on GM107 is very close to GK110, except the GK110_COMPUTE.UNK02C4 which is invalid and should not be used."
Nouveau has been making much progress on the compute support as of late. The Mesa 11.2 branching is set to happen on Friday and it's looking like NVC0 will still be left at GL 4.1 for this next release due to being blocked by the yet-to-land ARB_shader_image_load_store support.