OK, so because some people are acting dumb, this needs clarified: No, your current Sprint device with "800 MHz support" will NOT have LTE.
LTE will use a separate radio from CDMA, just as WiMAX and WiFi are separate radios. LTE is also Sprint's upcoming 4G network technology, while their current 4G network tech is WiMAX.
Now, your phones currently have three radios: WiFi and Bluetooth that runs on 2.4 GHz (and some run in the 5 GHz as well, aka dual-band WiFi Some devices have their WiFi+Bluetooth radios enabled to receive analog FM radio as well.), CDMA (1X/"2G" and 3G) that runs on 800-900 MHz, and 1900 MHz, and WiMAX on 2.7 GHz. These are all separate radios (for the purpose of this post, whether they're on the same chip or not is another matter). They cannot cross-communicate on each other's bands. So you can't run WiFi at 800 MHz (even though it'd mean you could easily get coverage in your entire neighborhood!), nor can you use CDMA on 2.7 GHz.
Currently, Sprint's network is like this:
800-900 MHz: Some CDMA 1X, mostly NEXTEL iDEN.
1600 MHz: Non-existant, owned by LightSquared, may or may not screw up GPS.
1900 MHz: Mostly CDMA 3G (EvDO), some CDMA 1X.
2700 MHz: Sprint/Clearwire WiMAX.
The short term goal (next two years) is this:
800-900 MHz: CDMA 3G/EvDO
1600 MHz: LTE (if the FCC, US DoD, and DoT give LightSquared their blessing)
1900 MHz: LTE
2700 MHz: WiMAX
The long-term goal (2-5 years):
800-900 MHz: LTE-Advanced (what 4G should have been, until all the US carriers basically bribed an international standards organization to say otherwise)
1600 MHz: LTE (see above)
1900 MHz: LTE
2700 MHz: ??? (Probably WiMAX still, for legacy devices/contracts, kinda like why we still have iDEN today)
Currently, Sprint phones have the following radio configurations:
800-900 MHz: CDMA (1X and 3G)
1900 MHz: CDMA (1X and 3G)
2700 MHz: WiMAX
So, your current phone won't get 4G LTE. It can't. It'll continue to get the old WiMAX 4G for the next few years, and will get better 3G as Sprint improves their network, but no LTE. Not ever. EVER. The Samsung Galaxy Nexus and LG Viper will be the first phones which support Sprint's LTE network, but will probably only support it on the 1900 MHz band. So those phones will have their radios setup like so:
800-900 MHz: CDMA (1X and 3G)
1900 MHz: CDMA (1X and 3G)
1900 MHz: LTE
Now, the real question will be whether the LTE radio will be integrated into the CDMA radio, allowing for easier switching between modes and an easier time on the battery (like how GSM devices can easily switch between 2G and 3G for battery savings, so would Sprint's LTE devices in this case), or whether LTE will just be a separate radio like how WiMAX is right now, and LTE is in Verizon devices.
NOTE: The above paragraph refers to the upcoming Sprint devices that support LTE. Your current device, no matter how much you twist words, Wikipedia pages, or anything else, will not support Sprint's LTE network. There is no magic button, switch, software update, or anything else.
