Cool move from the mosque. Not sure how much muslims do own some and are willing to spend bitcoin though. Eitherway, adoption is adoption and this gives us decent publicity so this is great news in my opinion.
Trust me, there is a decent amount of Muslims who have bitcoins.
In fact, people might use bitcoins for donating more then the other methods now because in Islam, the hidden charity is better then the one that people know about and bitcoin help achieving that since of its pseudonymous quality.