Just to set the expectations right: Arabic hardware keyboard and Arabic localization of pre-installed system and applications is not in the current plans. Never say never, but I personally doubt we will see this officially supported in Maemo 5.

I'm happy helping getting things done in the software side when it comes to push documentation or strings out. Yesterday I got a question about Catalan, which has common problems with Arabic and any non-supported language. It is expected that more volunteer translators from other languages will show up.