I downloaded and installed the Wordpress arabic version. I would also like to install the arabic version for buddypress. Does such translation exist? If it doesn't, where can I submit translations?
There is an Arabic translation according to GlotPress. This language is very incomplete at the moment, and you can help by following the instructions on the getting started section.
Good luck. BuddyPress has a very large POT file. Translating it is not a trivial job.