I'm not sure how much other HN'ers use Java in anger, but I really wouldn't classify the listed classes in the OP as something I wouldn't know from java.util.concurrent.
In fact some of those are things I do ask in interviews, which probably means that I would expect most Java devs to know about.
The whole "things you didn't know" series is aimed pretty low, more like "things you didn't know because you never used it at all". Was the same for the collections series.
No... I knew those things. Although from his analysis of CopyOnWriteArrayList, I'm wondering if ReentrantReadWriteLock is something he didn't know about java.util.concurrent.
In fact some of those are things I do ask in interviews, which probably means that I would expect most Java devs to know about.