Orfeo Toolbox (OTB) is a great symphony written in C++, or is it Opera ? I believe C++ in spite of its ceveats is one of the most portable langauages, a great choice for something demanding maximum output from the hardware such as an image processing application.
With inspiration from music with names such as orfeo and monteverdi, OTB puts together a fair few heavy weight projects. Not only in using them as libraries but being more than the sum of its parts. The developers also merge and maintain patched copies of these dependent projects in a mercurial repository ensuring a supported version is compiled against (a lot of the dependencies are merged from repository heads so much more recent than releases).
The dependencies are gdal, ossim, ITK, FLTK , OpenThreads, expat, liblas, etc. The cmake build system with the monolithic repository containing most of the other libraries makes getting up and running from a checkout relatively painless. Now I need to build the python and java bindings and try out some Qgis plugins and on demand image processing from GeoServer.