Chrome uses OS X's CoreText for rendering the tab titles, but uses its own text rendering engine for the site body. CoreText is the one that crashes on that unicode.
Very, very cool idea. The app works really well, but it feels a bit rough around the edges. I just spent about half an hour chatting with one of the cofounders though, J, and he seems very eager to improve the app, so I have all the faith in the world those edges will be straightened out. Keep up the good work!
They had already implemented it, but were using a way of keeping the app running in the background that's reserved for apps that play music or track your GPS location. Apple rejected the app because Sparrow was neither.