Created attachment 323282 [details, diff] darktable-1.0.5.ebuild.diff ebuild needs to add virtual/glu to {R}DEPEND to not fail in compile stage (configure does not check) with >=mesa-9.0
Your patch isn't entirely correct since opengl and therefore glu is an optional dep used only when the slideshow viewer is built. Fixed in CVS.
Thx, I must have overlooked that. :)