Hotmail has temporarily shut down the service that lets customers access Hotmail through the browser on mobile phones via m.mail.live.com. We apologize for the inconvenience and will bring back the service shortly once maintenance has been completed.
Update:
We have completed maintenance on Hotmail’s mobile browse service in the majority of geographies. For the few remaining customers we are working to bring the service back in the near future.
Hotmail team blog archive 