Potential trouble is, unless I'm mistaken, Arabic is read from right to left (right, Hedaya?). I have no idea if any of the native languages for those devices are made for that (and your previous experiences seems to indicate : not yet.)
One potential solution, if your at ease with technology, would be to 'root' your device (Sony T1, or a good lot of different Nooks, see the Nook forum) to a complete Android build and use an application such as FBReader (the regular version supports right-to-left languages, I *suppose* the Android version might as well) or a specialized one (there's a 'Arabic epub reader' app for sale on the android market at about 2.50$ and I'm sure there's a lot of others but then I don't read Arabic and the descriptions ARE in Arabic
