Who said the iPhone 4S was "4G"? Not Apple. Maybe ATT who is calling their HSDPA+ "4G," even though it's 3.5G, but Apple is clearly not marketing the 4S as a 4G phone.
Read what you link to.
Standard HSDPA (HSPA) runs up to 14.0 Mbps.
The iPhone is an HSPA+ (evolved HSPA) device as it runs HSDPA at 14.4Mbps.
The ITU changed the definition and said providers can call HSPA+ 4G.
From a marketing perspective, it's 4G.
Reality, it's 3.75G
We all know AT&T and T-Mobile call anything using HSPA+ a 4G device.
Hell even Verizon and AT&T's LTE deployments don't meet the 4G spec.
They're 3.9G
Sprint's WiMax is only 3.75G and is slower than HSPA+.