Mobile carriers are testing an iPhone with LTE capability, reports Boy Genius Report, the recent king of Apple-related leaks. It even has action shots of code that it says are a smoking gun.

Why should we care about 4G LTE? First, a quick refresher one why this is exciting (at least, to geeks who get excited about such things). LTE, which stands for Long Term Evolution, is an extension of the GSM technology currently used around most of the world. A few Android phones already use it. Essentially, it’s the next major communications standard, and it’s going to make everything faster. In theory, at least, it could offer 100 Mbps download, which MacLife points out “runs circles around current mobile speeds and even eclipses most home broadband.” (In reality, in the near-term, LTE speeds won’t move at such a clip; Verizon promises 5-12 Mbps.)

With the promise of such speeds, everyone has been wondering when 4G LTE will be coming to that totem of modernity, the iPhone. And with an iPhone 5 release nearing (sometime in September, say most sources), everyone’s wondering in particular if the next iPhone might employ the new standard. Does BGR’s finding mean a 4G LTE iPhone is imminent?

In a word, unlikely. Kudos to BGR for digging up proof of the fact, but it should come as no surprise that Apple’s carrier partners are testing a 4G LTE model of the iPhone. As Eric Zeman of InformationWeek puts it succinctly, “Well, duh.” Testing takes time, he points out: “Dan Mead, Verizon Wireless’s CEO, said in January when the company announced the iPhone 4 for Verizon Wireless that it tested the iPhone 4 for a full year before launch.” LTE is undoubtedly the future of communications, and we’d be surprised if all major players in telecommunications weren’t testing such devices. What might be more useful would be to know for how long carriers have been testing this LTE iPhone–but BGR doesn’t illuminate that matter.

It’s fun to speculate about the imminent iPhone 5–and there are no shortage of people doing so. But it’s probably best to hedge our bets, and lower our expectations. Apple’s COO has said Apple wouldn’t rush headlong into the new standard, until it could do so without making design concessions (currently, 4G LTE is a major drain on battery life, and Apple surely has no desire to make the next-gen iPhone suddenly bricklike to maintain current battery expectations).

For our part, we’re inclined to agree with ZDNet’s Rachel King, who thinks it might be premature for a 4G LTE iPhone. The next-gen iPhone might really be a “filler” model, she suggests, in the way the 3GS was, prior to the release of the iPhone 4. Only time will tell, but the point remains: If you’re eager for a 4G LTE iPhone, it’s certainly on the way–but you’d better not hold your breath.