I posted something to this effect on Hirhurim, but Simcha appears to have removed his comments feature. In any case, I think it's worth repeating.
The question that arose was, should Jews commit time and money to causes that don't specifically benefit other Jews. I think there's a case to be made for either side. None of us have unlimited supplies of time and money. We can't help everyone. There is merit to the notion that "charity begins at home;" if each community took care of its own needy, the world would be a much better place.
On the other hand, many needy people are not cared for by their own. While I think that it is respectable for a Jew to decide to donate primarily to Jewish causes, he or she must be careful not to allow that policy to become an excuse for ignoring the suffering of non-Jews. What does it say about me if I turn away from the local homeless man because he isn't Jewish? Will the quarter I didn't give him go to a worthy Jewish cause, or will I spend it to upgrade to a larger size caramel latte? How much time does it take to send a few letters on behalf of the residents of Darfur? What will you do with that time if you don't send the letters?
As always, I intend this mussar for myself as much as anyone.
Correction: Simcha did not remove his comments feature. For some reason I was simply unable to view the comments the last time I visited the site.