Johan Djourou spent the second half of last season with Hanover, after Arsene Wenger deemed him surplus to requirements in London. He did pretty well there - I didn't follow him, but Hanover seemed pretty happy with his play, and now that has been parlayed into interest in a season-long loan. Arsenal would rather sell Djourou and get him off the books, and this is where the words "Johan Djourou" and "bidding war" coexist in a way you probably never thought they would - Hanover has expressed interest in a year-long loan spell, but another club, Hamburg, is keen on Johan and is open to the possibility of buying him outright.
Djourou's a useful player who never really found a role at Arsenal; I have no doubt he could go to Germany and do a job for whoever decides they like him enough to take him on permanently.
And with that, the summer clearout starts to gain some momentum; Arshavin, Squillaci, and Denilson gone, Djourou probably out, Bendtner hopefully next, and there's still a few weeks until preseason starts. Say one thing for Arsenal's summers, they're rarely boring.