The well known and popular leader of Hamas is Sheikh Hassan Yousef. The Christian press is full of the fact that his son Masab Yousef has converted to Christianity and has moved to California. Read his testimony on this link and listen to the Fox News interview here.
These stories do the rounds, but attempts by his family to re-convert him suggest that it is true.
I hope that this is a true conversion, although I would be more convinced were he living in Malawi than in California.