As requested by Apple in the next February (February 2014), every app submitted to AppStore needs to support Arm64 architecture. In my project, I used many static libraries (*.a) and I can check if these libs support arm64 arch. However, I don't know if some frameworks such as Facebook.framework supports this new arch. How can I check it?
Each framework is really just a directory - not even like a package directory, but a plain directory you can browse directly into with Finder. Go into the .framework folder, at the top level you'll find a file with the same name as the framework (for older frameworks that file may be located under a folder called Versions/A within the .framework folder).
That file is really a static library (.a) file, just without the extension. Check it as you would any static library (using file or lipo -info) and you'll see what binaries the file contains.
You'll also know through XCode though. If you switch your project to support arm64 and the libraries you are linking to do not have arm64 support, XCode will not finish linking when compiling for a device.