I have always been curious about Google and what its applications are based on. It turns out it's Java, Python, C++, and SWIG. SWIG is used to tie Python and C++ code together. Here's an entire transcript from PyCon 2005 that details what exactly Google does with its software.

TITLE OF PAPER: Python at Google
URL OF PRESENTATION: --not available--
PRESENTED BY: Greg Stein
REPRESENTING: Google

CONFERENCE: PyCon 2005
DATE: March 25, 2005
LOCATION: Marvin Theater
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Recently someone was making a claim that semantics and syntax are by far the most important parts of knowing a language, I have to say I disagree almost completely. Knowing syntax and semantics of a language is almost useless — for instance I can write you some python (I am familiar with the syntax, definitions, indentation, etc.), but I could hardly implement a common search algorithm that I could implement in C, or heck even assembly. When you start learning a language the semantics and syntax are important.More ... >>