T-Mobile announced that if you buy a tablet from T-Mobile you can get up to 200MB of LTE data every month. Roaming and International data are not included in the new T-Mobile "Tablets Un-Leashed" program.
Tablets that are compatible with T-Mobile's HSPA/LTE network are eligible for the free data. T-Mobile voice plan customers can buy 500MB of data for $10 a month.
After using up the 200MB of data, there is not throttling however the customer can buy more data by data passes.