Sprint has announced the latest addition to their small-but-growing lineup of 4G LTE capable smartphones. The LG Viper 4G LTE will be available for pre-order from Sprint’s website beginning Thursday, April 12th. The LG Viper is the second 4G LTE-capable smartphone Sprint will offer, after the popular Galaxy Nexus.

The LG Viper features a respectable feature set. It comes with a 1.2 GHz processor, 1GB of RAM, and 4GB of on-board memory with a microSD card expansion slot. It also sports a 4-inch display made with Gorilla Glass, a 5 megapixel rear camera with LED flash, and a VGA front camera. It runs on Android 2.3 Gingerpread. It also includes mobile hotspot capabilities. As previously noted, the LG Viper will be compatible with Sprint’s 4G LTE network when it begins to roll out later this year.

In addition to the phone itself, though, Sprint slipped in a very interesting detail about their data plans once the switch to 4G LTE is made. It seems that Sprint intends to offer unlimited 4G LTE data plans. With AT&T and Verizon having abandoned the practice some time ago, Sprint is currently the only U.S. carrier to offer smartphone users unlimited data mobile data plans. There had been some speculation as to wether they would continue the practice once they began upgrading to 4G LTE. It seems that they will.

This has interesting implications for owners of both iOS and Android smartphones. AT&T and Verizon currently offer tiered data plans that restrict the amount of data a user can download in a given month. Once that cap is hit, the user has to pay a hefty fee to get more data. While those data caps are often not terribly onerous for users with 3G phones, it can be a lot easier to hit your limit on a 4G device (as owners of the new iPad have discovered to their frustration). What it boils down to is, just as a 2GB or 3GB data plan means a lot less on a 4G device than a 3G device, an unlimited plan means considerably more.

What’s more, unlimited data plans may have an impact on the launch of the next iPhone. There have been rumors that Sprint will be getting the iPhone at launch this time around. What’s more, it’s pretty much a given that the next iPhone will be a 4G device. That means that when the next iPhone launches in September or October (probably), prospective buyers will have a 4G carrier that gives them back the chance to have an unlimited data plan. Sprint is no doubt hoping that will make some loyal AT&T and Verizon customers think twice about going back to their old carrier.

What do you think? Would you consider switching to Sprint for an unlimited 4G data plan? Why or why not? Let us know in the comments.