The Terminal displays the Arabic text just fine (no boxes or question marks) but the problem is that it displays each character alone (not joined by the letter after it) that is because Arabic is cursive (http://en.wikipedia.org/wiki/Cursive) language. I was able to join the letters using http://www.arabeyes.org/project.php?proj=BiCon but the fact is that I need another software to just view the text properly is considered a bug (at least to me), so may be you could take a look at that bicon and may be you could fix that annoying bug? it practically makes the text unreadable..by the way, by fixing this you aren't fixing Arabic only but another languages as well, like Urdu, Kurdish and any language that uses the Arabic alphabet.. See an image of what it looks like..I wrote the joined text so you can compare.. http://img218.imageshack.us/img218/5974/unjoinedgw9.png Thanks
This is definitely a VTE/Pango issue, please file a bug report on bugzilla.gnome.org.