Actually choice of language is influenced by factors like:
1. Language that all your team members are comfortable with.
2. Existing technology that the company is using.
3. Easy for developing prototypes
4. Mandatory language for the targeted platform
(this is all that came to my mind while writing this reply)
I work in a mobile gaming company where we develop mobile games for numerous platforms. To be honest I simply love Java and C++. My choice of language depends upon the targeted mobile phone. But whenever I need to test out an algorithm or need to make some prototype, I use Java. For server side programming I again use Java because I love Servlets/JSP. It takes care of most the headaches.
Still there are some parts of the code which needs to be written in C,C++ when every single CPU cycle and every single byte becomes important