If I understood the explanation on that article correctly, what's even more interesting is that this typo apparently hasn't yet been fixed in the repos (assuming I'm looking at the right ones).
There are 2 repos which I looked at:
https://github.com/slockit/DAO
https://github.com/TheDAO/DAO-1.0
I don't know which one is the authoritative one. But the interesting bit is both these repos still have that same typo in the master branch:
https://github.com/TheDAO/DAO-1.0/blob/master/DAO.sol#L666
(the other repo) https://github.com/slockit/DAO/blob/develop/DAO.sol#L685
The slockit account repo has a commit which was made 6 days back, with the commit message "Protect against recursive withdrawRewardFor attack" https://github.com/slockit/DAO/commit/f01f3bd8df5e1e222dde62... but it doesn't fix the typo and there aren't any more commit in there after that one.
Does this mean, the upstream repos containing the typo haven't yet been fixed? Or am I just looking at the wrong repos/branches? Or did this typo get known only a few hours back?