Somehow I seriously doubt this.
My Verizon LTE connection averages around 20 -30 mbps, but LTE is still no very widespread, Verizon and AT&T still don't have a lot of LTE subscribers and when you consider other customers most of which are on HSPA+ or HSPA, it becomes much harder to believe I have a HSPA+ 21 S2 on AT&T as my work phone and it averages about 7-8 mbps, the iphone 4S has a maximum speed of 14.4 mbps.
Are they averaging the theoretical maximum of a carrier's service or the average download speed users actually see?
In the article it's self they talk about how many carriers advertise speeds above 21mbps.
I think this is a trick to make carrier's look better than they are in real life.
Globally, most places are 14.4 HSPA+ or 21 HSPA+. Some countries are still using GPRS or EDGE, but the standard is pretty much 14.4 or 21, with the exceptions being LTE and GPRS/EDGE-only.