Are libraries reasons? If so, then I'd say Boost deserves at least a nod.

Edit: I wanted to add some evidence, but the job looks to have been filled. The current opening lists C++ but doesn't mention Boost. Last week though...

http://tbe.taleo.net/NA11/ats/careers/requisition.jsp;jsessi...

(these guys are across the street from my old office - good people, from what I hear)