This comes hot on the heels of Baidu rumors that they were looking to buy an English-language search engine. Whether the FB deal interferes, precludes or supplants Baidu's English-language intentions is unclear.
Baidu is China's most popular search engine. And Google's troubles in that market are well documented, too, so that probably won't change anytime soon.
The Facebook-fueled deal would provide China with a jointly owned social networking site -- facebook.com would not be a valid URL there, as most social networking sites are blocked. With good reason, if you're in government and your people might be looking to organize.
This puts FB in a huge market as Baidu leverages someone else's social-network building skills. A proverbial win-win.