From the beginning of February, T-Mobile customers will have their data usage limited to just 500MB per month, down from a current maximum of 3GB.
According to a statement on the T-Mobile website, this fair use policy is there to ensure that T-Mobile customers will "always be able to browse the internet". Thought you already were browsing the internet? Apparently not, as the statement goes on to explain "browsing means looking at websites and checking mail, but not watching videos, downloading files or playing games". Or at least it does now, if you're a T-Mobile customer.
So, what are your options if you want to do more than, ahem, browse? "If you want to download, stream and watch video clips, save that stuff for your home broadband", says T-Mobile.