Reproduced on Debian GNU/Linux 7.5 (wheezy) 64bit, Microsoft Windows XP (32bit, latest SP), multiple hardware configurations using Nvidia, AMD or Intel graphics.
Broken: current 2.71 release build (9337574) from download.blender.org, latest 2.71 BuildBot build (5e3e095).
Short description of error
The location of the active object in world space affects the result of Cycles' object space normal bake pass. The bake result is correct only if the object is at location (0, 0, 0) during the bake. For any other location the bake produces normal maps that bear no resemblance to the sampled geometry.
Exact steps for others to reproduce the error
Open the attached objspacebug.blend file and click the bake button.
Although the seven objects in the scene re-use the same mesh geometry datablock with no modifiers attached, each bake turns out different. Only the object in the center produces a usable object space normal map.