"T-Mobile has cut by more than half charges for business customers who transmit data over its mobile networks in countries where it operates its own network." (from the reg)

If you are on a T-mobile business tariff and travelling in Austria, Czech Republic, Croatia, Germany, Hungary, Netherlands, Poland, Slovakia and the UK you will benefit from this price cut, there are a couple of exceptions. "Officelink" customers and customers using BlackBerry or Sidekick devices will not receive the same price cuts. The countries listed above are where T-mobile operates it's own network, Max Miller the head of carrier services at T-Mobile said they are negotiating with other carriers to try and get discounted prices elsewhere.

If the cost of data transmission continues to fall and availability of VOIP enabled handsets improves customers will be able to use their data allowance to place cheaper calls back to the UK and to other countries using technologies like Skype and SIP.