Even 12Mbps doesn't sound super fast to me. In Canada we've had real world speeds higher than this from most carriers since the start of 2010. Even on our newest budget network (WIND Mobile) I've gotten real world speeds of 7Mbps on my N900.
T-Mobile has even recently been started calling HSPA+ (21Mbps) as 4G. Well why not, if you think "up to 12Mbps" is 4G.
Our major carriers will be rolling out 42Mbps+ (not sure what real world speeds will be) HSPA soon, and they are still calling it 3G. It's only marketing in the US that pushes the definition beyond ITU standards.
I just find it funny that what US carriers call 4G is actually slow than most 3G networks around the world.