The Sony Ericsson Xperia X10 has passed through the FCC (Federal Communications Commission). This is normally a pre-cursory step before any wireless device lands in the United States. Hopefully this means that a worldwide Q1 2010 release date is intact. Interestingly, the tested UMTS bands were I, IV and VIII, or in other words 900/1700/2100MHz. This implies it will be compatible with T-Mobile US.