OK, while this is not exactly HOT of the press, it is still warm!
Early last month the Spanish data protection regulator fined Twitter €30k for breaching laws governing the use of cookies. Specifically, Twitter used an implied consent mechanism to obtain consent from its users to use cookies, and did not provide a reject option or a mechanism to mange or configure cookies.
Although the fine was issued in Spain, it is likely that many of the other EU regulators would have reached the same conclusion so, remember to ask your users for their consent before you serve them cookies!