As I’ve found with most of the major Web-apps out there, including social media giants like Facebook and others, Unicode support is far from complete. I’m not a big MySQL guy, but have been building some stuff lately and ran into this:
http://dev.mysql.com/doc/refman/6.0/en/faqs-cjk.html#qandaitem-22-11-1-16
Basicall MySQL version < 6.0.4 doesn’t support characters outside the BMP (Basic Multilingual Plane) which seems to be a common pattern for a lot of software. The BMP is all code points 0×0000 to 0xFFFF, however, Unicode stretches far beyond to 0×10FFFF. It makes sense I suppose, after all the BMP is made of the most commonly used scripts, the stuff beyond it (supplementary) are usually considered rare.