Hi,
I have a question regarding the libmv library. I have seen that there is an offical github repository for libmv but last time it has been updated was back in 2014. The library in the blender source code seems to have recent bugfixes but it is not a submodule. My question is if I can use the blender version of libmv or is it recommended to use the unmaintained project? Is libmv an offical blender project?
Have a look at https://developer.blender.org/tag/libmv/
Note as of 5/2015: Previous libmv sites are deprecated (Google Code & GitHub); this page and developer.blender.org are now the official home of libmv.
Development
libmv is officially under the Blender umbrella, and so is developed on developer.blender.org. The source repository can get checked out independently from Blender.
TLDR: libmv is developed on developer.blender.org and an official blender project.