So which languages are going to succeed in the world of High Frequency Finance? Well you can bet your bottom dollar it's not going to be C# or C++. Both generate buggy and leaky solutions and are too reliant on third party libraries of unknown veracity. You can also rule out the raft of scripting languages - no matter how much the developers like them: Perl, Python, Ruby et al have good geek factor, however they don't cut it in production systems.
So we're left with C and the functional languages. C is considered as a weird throwback to the 70's by most nascent programmers. What most of them do not realise is that the C# CLR, Java Virtual Machine (parts of), Ruby, Perl, Python, Apache, Linux, Solaris, C++ etc etc are all written in C. The main reason for this is performance, simplicity, robustness. C has it's share of problems, but in general it's a fairly good language.
So, why are all the quantitative libraries in Investment Banks written in C++? And why are they mostly single threaded? The answer is hubris on the part of the programmers and, as previously outlined, the difficulty in coding thread safe libraries.
Well, times have changed I'm afraid. C++ has to die because it does not translate into hardware - a route where tremendous performance gains are to be had. C is looking weak in light of the scalability models which can take advantage of multi-core within the functional languages. The future in the short term is C but watch for the rise of Erlang and Haskell. Their time has come.