http://www.securelist.com/en/blog/667/The_Mystery_of_the_Duqu_Framework

Conclusions
The Duqu Framework appears to have been written in an unknown programming language.
Unlike the rest of the Duqu body, it's not C++ and it's not compiled with Microsoft's Visual C++ 2008.
The highly event driven architecture points to code which was designed to be used in pretty much any kind of conditions, including asynchronous commutations.
Given the size of the Duqu project, it is possible that another team was responsible for the framework than the team which created the drivers and wrote the system infection and exploits.
The mysterious programming language is definitively NOT C++, Objective C, Java, Python, Ada, Lua and many other languages we have checked.
Compared to Stuxnet (entirely written in MSVC++), this is one of the defining particularities of the Duqu framework.