It's written in C, but their provided Makefile does not generate a shared library. However, it looks pretty easy to compile, just do:
gcc -fPIC -shared -O3 -o libsift.so src/lib*.c since it looks like all of their "library" code is in files named src/lib*.c Then you can do ccall((:sift_compute_points, libsift), ......args and types....) to directly call functions in the library. The API looks straightforward to access in Julia.
