It serves pretty much the same aim, i.e. production of energy by ATPase. One can thing about it as being flipped (inside-out) in comparison to mitochondria or as analogy with cristae being stroma.
One more thing that came to my mind. RuBISCO is activated by increase of Mg2+ concentration. I’m not sure how this proceeds, as it was always covered in lectures simply as increase of Mg2+ ions, but it could be related to chemiosmosis http://en.wikipedia.org/wiki/RuBisCO#Re … c_activity