How Old is Arsenal Target Salomon Kalou?

Arsenal are in the hunt for Chelsea striker Salomon Kalou, according to reports in the British media.
Despite the fact that this transfer rumor makes absolutely no sense whatsoever from Arsenal's perspective (they already have Arshavin, Van Persie, Eduardo, Walcott, and Bendter - not to mention Wilshere and Rosicky) it does perhaps stir up a new African footballer age controversy.