Apple doesn't currently make or market an iPhone 4G but given recent North American marketing shenanigans by the carriers, they might just get one sooner than anticipated. There was a time, you see, where 4G applied to really fast, really next generation mobile connectivity, like fully implemented voice/data LTE approaching 100 Mbps. Then Sprint launched Wi-Max as 4G. Then T-Mobile rebranded HSPA+ as 4G. Then Verizon deployed early stage LTE as 4G. Then AT&T rebranded their slower HSPA+ as 4G. 100 Mbps got shoved aside, and 21 Mbps, even 14.4 Mbps became "4G". Canadian carriers, which had previously called their 14.4 Mbps and even 21 Mbps HSPA+ networks "3G" have recently rebranded them to "4G" as well so as not to seem old and outdated. (For more on what all these terms mean, check out our networking glossary.)
No doubt it's easier to change a name than change a network, and easier to slap the letters 4G onto a phone than actually getting a real, power efficient, lightning fast 4G radio into one. But that's no excuse.
Verizon is arguably the closest with their early stage LTE deployment and phone like the Thunderbolt that don't get great battery life but do get amazing speeds.
My counterpart over at Android Central, Phil Nickinson has done a review of the Verizon LTE HTC Thunderbolt (and also told the carriers to kindly cut out the 4G smoke in our eyes), while PreCentral.net's Derek Kessler has just reviewed the AT&T HSPA+ HP Veer 4G.
...Especially since the CDMA version on Verizon will still be "3G" EVDO Rev A for another generation.
That's a huge competitive advantage, but hugely confusing for users.