Apple has been quite reluctant to adopt the the LTE technology, which could bring even faster data speeds to their devices. Their main reasoning for not supporting it thus far is that Apple refuses to make design changes to accomodate the 4G LTE network. Lack of chipsets, device speed and power are amongst the items Apple would need to address. MacRumors states that "LTE chips suitable for Apple's needs are reportedly set to debut in early 2012."
With all that in mind, BGR has discovered that Apple is currently testing an LTE-enabled phone with carriers, below is an excerpt from their findings:
"While we can’t confirm that the upcoming fifth-generation iPhone will be able to support 4G LTE, we can now exclusively confirm that Apple’s carrier partners are testing iPhone models with LTE capability. BGR has obtained evidence of an internal iOS test build from one of Apple’s major carrier partners, and buried in the firmware is a property list (.plist file) for LTE. This doesn’t necessarily mean every Apple device that’s about to be released will feature an embedded 4G LTE modem, but it certainly means Apple isn’t sitting on the sidelines as 4G LTE networks continue to roll out around the world. Plus, when Apple finally does make a 4G LTE device, the battery might actually last longer than a few hours. Check out our photo gallery for images of Apple’s LTE plist file."
It's unclear at this time if the iPhone 5 will release with full 4G LTE support, but it should be noted that t is expected to support HSPA + technology for GSM networks, which some carriers label to as 4G.
What are you expectations when Apple finally does hop on the LTE train?