T-Mobile has quite a few things up their sleeves right now.
First off, T-Mobile finally unleashes their 3G Network. It was available for testing purposes in New York but now will be available in the major cities in U.S.

Click here to see T-Mobile’s 3G Coverage Map

Let’s get a quick breakdown of the most commonly used networks by your provider:
note: Kbps stands for Kilobytes per second.

Edge: Enhanced Data rates for GSM Evolution (or Enhanced Data GSM Environment)
Edge Speed: Ideally 200 Kbps, realisticly its closer to 90 Kbps

GPRS: General Packet Radio Service (an upgrade from GSM network). This is 2.5G that gives the speed between 30Kbps – 50Kbps

UMTS: Universal Mobile Telephone Service. This is the 3G Service provided by T-Mobile and ATT. This service is aimed to provide up to 2Mbps but in the real world, you’ll see 300Kpbs – 400Kbps (which is still an amazing speed compared to Edge or GPRS).