Most of amazon.com systems are written in perl mason. Very few systems use c++, I would say not a single major system at Amazon is written in c++. It definitely should not be included in this list
I worked in Supply Chain specifically on the FC side of software (OK...specifically on COFS for those of you who remember) from 2004 till 2007 before moving over to retail. And I can say that all FC software was C and C++. There were small pockets of Java when I left, but I'd be really surprised if ALL of FC software has been ported to Java in the last 4 years. You're talking about 10+ years of software. Software that controls hardware that works as is. Tons of "bugs" and "features" to port.
And I'd call the software that runs the warehouses a major system.
My team tried to replace a C++ daemon with a Java one and our favourite phrase became "Oh yeah. Forgot about that business rule".
Oh, and there's at least one critical service written in Erlang =D
There was a time when Amazon was mostly C++, but it wasn't very recent.