That is interesting indeed. If you go on to page 2 of the rankings* you can see that there were indeed a large number of Haskell, Python, Lisp and Ruby entries, but the top 100 (and especially the top 25) are totally dominated by C++.
The other thing I find interesting is the lack of Java entries. Java is as widely-known as C++, but there's only one Java entry in the top 100, and even in the top 200 Java is only about as common as Haskell or Ruby, and far less common than Python.
The problem with Java was that it was impossible to get it running fast enough. You had 1 second of thinking time, but with Java you could barely access 0.05s, while compiled languages like C/C++ or even C# could easily use 0.95s without having any timeouts (which leads to disqualification).
My impression is that as long as you can ignore startup time, Java in general is pretty close to C++ and definitely much faster that Python. I am surprised this would be a problem with Java and not with Python. Did anyone had the same problem with Python?
The contest site had a problem with their JVM which interacted badly with their sandboxing environment. The 1-second time limit would disqualify any Java entry that took something like 50ms or more for some unknown reason.
It might have something to do with the blatant warning on the entry page telling you not to use Java due to some mysterious problem with it and their sandbox.
The other thing I find interesting is the lack of Java entries. Java is as widely-known as C++, but there's only one Java entry in the top 100, and even in the top 200 Java is only about as common as Haskell or Ruby, and far less common than Python.
* http://csclub.uwaterloo.ca/contest/rankings.php?page=2