Hunh. The emphasis on C++ over Lua surprises me. Maybe the indie guys I tend to talk to are a bit more Lua than the industry as a whole. I'd love to hear some thoughts from people inside.
Generally a big-budget game will have its engine written in C++ and a scripting language used for gameplay logic (sometimes the AI too). The gameplay logic is often written by level designers who aren't necessarily programmers by trade so a high-level language is often required, and so visual programming languages like Unreal3's Kismet are starting to take over from traditional scripting languages like Lua. Whatever the choice of scripting language, the amount it's used is a balancing act with productivity and flexibility on one side and raw speed on the other.
I think you're correct in saying that indie studios use scripting languages more than the industry as a whole. Indie games typically don't need to push the hardware so they can usually afford to use higher-level languages, or they use a C++ engine but do a whole lot more in the scripting language.
C/C++ are generally still the "fastest" languages in terms of final application performance. And, I am pretty sure that all of the DirectX/OpenGL APIs are still tied pretty tightly in with C/C++ libraries.
