From a technical perspective, 4G is already largely in use throughout the world. HSDPA+ is considered 3.5G or 4G (depending on where you reside) and in most areas is deployed. 4G LTE is the latest connection type, supporting speeds up to 75 Mbps, where as HSDPA+ supports up to 21, or 44 in some iterations.
So I guess what everyone should be waiting for is not 4G to be invented, but for it to arrive in your area. As mentioned above, LTE speeds are typically only found in larger cities world wide (and only in about two cities in all of Canada at present!)