I've posted about this above a little after you did. Reading the article, I'm unable to determine whether or not this has any practical utility outside of niche applications or if it has the potential to be broadly useful. Has anyone reviewed the SDK that can render an opinion?
Homomorphic encryption is broadly useful and in fact should be ubiquitous for remote computation that leaks private data (not to comment specifically on Apple's implementation). They did open source it though, which gives you an idea that they want others to follow.