Updated: We changed the speed data to reflect carrier-reported speeds for all four carriers, on January 26, 2010 at 1 p.m. Eastern.

In 2011, wireless carriers are banking on you going 4G with your next smartphone purchase.

Verizon says it will release 10 different 4G-enabled handsets in the next year. AT&T says it will double that number, with 15 of its own offerings being Android OS-based devices. And T-Mobile, which offers a handful of 4G phones, claims its network is "America's largest 4G network."

But with all the wireless industry jargon being thrown around in marketing campaigns these days, it's still unclear just what each carrier means when it touts its network as "4G."

Let's take a look behind the fog of marketing jargon that U.S. customers face today.

4G Technologies —————

Loosely defined, 4G stands for the the fourth generation of cellular wireless standards. In the narrow terms originally defined by International Telecommunication Union standards, it doesn't count as 4G unless it offers download speeds of 100 Mbps to 1 Gbps. That's about 100 times faster than any speeds we're seeing on networks now.

If we were to judge the networks available to us now by this standard, none of them would be considered 4G.

Luckily for the carriers, we aren't judging that way – at least, not anymore. In December at the ITU World Radiocommunication Seminar in Geneva, the ITU allowed the term "4G" to "also be applied to the forerunners of these technologies, LTE and WiMax, and to other evolved 3G technologies providing a substantial level of improvement" compared to current 3G networks.

AT&T wasted no time embracing the new nomenclature, relabeling its network overnight.

And well it might, as rival T-Mobile has been using the same nomenclature for the same technology since early 2010.

Before we delve into each carrier's offerings, let's review the competing technologies being used today.

WiMax

Developed by the IEEE, WiMax is one of two competing technologies to blaze the 4G trail. WiMAX, also known as 802.16, is in the same family of standards as Wi-Fi. Sprint and Clearwire own the biggest share of the 2.5-GHz spectrum – "the most readily usable licensed spectrum in the United States," according to information site WiMax.com– across which WiMax is carried.

LTE

LTE stands for long-term evolution, the leading competitor to WiMax for next-generation wireless data. Instead of expending efforts deploying a new network infrastructure – like Sprint has done and continues to do with WiMAX – LTE proponents like AT&T update existing 3G networks. While the WiMax network is more fully developed at the moment, LTE won't be widely available until 2013, according to forecasts from both AT&T and Verizon.

HSPA+

This is where it gets a bit tricky. High-speed packet access, or HSPA, is a third-generation (3G) data technology that's widely used today. A faster version, HSPA+, has been widely considered 3.5G, until the ITU decision in December opened up those terms to a more liberal interpretation. Sprint, Verizon and AT&T weren't happy. The technology is an incremental approach to upgrading existing HSPA networks, not a whole new generation of technology.

Still, the ITU decision means carriers can start referring to their HSPA+ networks as 4G.

Let's take a look at the big four U.S. mobile carriers and the flavors of "4G" they're boasting.

Sprint ——

Launched in June of last year, the HTC Evo was the first WiMax smartphone to appear commercially within the United States, as well as the first 4G-capable smartphone to hit Sprint's network. With its attractive $10 a month unlimited 4G data plan, Sprint's bottom line is the figure to beat.

Technology: WiMax

Claimed Speed: 3-6 Mbps down; 0.6-1.4 Mbps up, with peaks of 10 Mbps down; 3.1 Mbps up

*Data Plan Cost: *Unlimited premium data for $10/month, on top of 3G data plan charges

*Availability: *Currently available in more than 70 markets

T-Mobile ——–

It wasn't a year ago that saw T-Mobile pimping itself out as the nation's "largest 3G network." But since 4G became the new black, T-Mobile started boasting "4G speeds" on its HSPA+ network, eventually relabeling the network itself as 4G.

T-Mobile ranks fourth in the United States among wireless carriers, but doesn't want to be in that spot forever. The company will position itself as an "affordable data services" company in 2011 and beyond, according to Rene Olbermann, CEO of parent company Deutsche Telekom. T-Mobile plans to add more than 25 4G devices in 2011, including the Samsung Galaxy S 4G,

*Technology: *HSPA+

Claimed Speed: 5-10 Mbps down

Data Plan Cost: Unlimited data for $30/month; 200 MB/month for $10. Pre-paid plans also available.

Availability: Wide availability, with over 100 major cities covered by the network.

Verizon ——-

Just recently launched in December, Verizon's fledgling network measures in at the smallest, with service provided to 38 major metropolitan areas across 22 states. The company plans to expand its coverage nationwide by 2013. With a suite of 10 4G devices announced at CES in January – including HTC's mammoth Thunderbolt smartphone and the sexy Motorola Xoom tablet – we'll have to wait and see if network expansion can keep up with customer demand.

*

Technology:* LTE

Claimed Speed: 5-12 Mbps down; 1-5 Mbps up

*Cost: *Unlimited data for $30/month; 2 GB/month for $20. Prepaid plans also available.

*Availability: *38 metropolitan areas across 22 states

AT&T —-

AT&T has rebranded its enhanced 3.5G network with careful caveats that claim "4G speeds" rather than naming the HSPA+ network itself 4G. But unlike T-Mobile, AT&T is following in step behind Verizon with plans for LTE upgrades to its network to be completed by 2013 (just like Verizon). As of today, AT&T has deployed HSPA+ to "virtually 100 percent of its mobile broadband network," company spokesman Seth Bloom told Wired.com in an e-mail, "which enables 4G speeds when combined with backhaul."

Technology: HSPA+, roll-out to LTE in 2011

*Claimed Speed: *6 Mbps down

Cost: 2 GB for $25/month; 200 MB for $15/month.

Availability: HSPA+ is widely available across continental U.S.; LTE to be rolled out mid-2011, fully deployed by 2013.