If your total data usage in any billing cycle is more than 1GB, your data throughput for the remainder of that cycle may be reduced to 50 kbps or less. Your data session, plan, or service may be suspended, terminated, or restricted for significant roaming or if you use your service in a way that interferes with our network or ability to provide quality service to other users.

So, why did T-Mobile implement the cap initially? Hansell quoted T-Mobile as saying:

We have a responsibility to provide the best network experience for all of our customers so we reserve the right to temporarily reduce data throughput for a small fraction of our customers who have excessive or disproportionate usage that interferes with our network performance or our ability to provide quality service to all of our customers.

Read the rest of this article on eWEEK.com.