Here are some FAQ from BBC:
Why is BBC Radio changing the audio format across its radio streams? We are restructuring our distribution methods that will allow us to offer a low cost simple solution and one configuration that can work across all platforms leading to a more efficient, reliable and improved delivery process.
Further information can be found at http://www.bbc.co.uk/blogs/internet/entries/28dfd220-7ca1-3683-ac16-3938cfb4b882
Will the change in format affect my internet radio? Yes, some radios will be affected. BBC national radio stations and local radio services are available to listen to live if your internet radio supports a format called SHOUTcast MP3. The World Service is no longer available using windows media and has changed to HLS a format incompatible with internet radios). The BBC has released high quality streams for all stations in a format called HLS and we are working with the manufacturers to implement this across all devices. If your radio does not support SHOUTcast MP3 you will not be able to listen to BBC radio services.
The BBC seeks to provide the best audio formats to licence fee payers and will continue to review its distribution methods in order to offer the best listening experience to its listeners.