Microsoft's My Phone backup service for Windows Mobile devices has shifted into public beta, meaning that anyone can now sign up and test out the system. My Phone uses an on-device backup client to synchronize contacts, calendar entries, SMS messages and media with the cloud, as well as offering a web interface through which they can be viewed, edited and added to.
Up until now, the service had been in closed beta status, with only those whom Microsoft invited to take part able to access it. Currently it's free to sign up to and try, though we imagine that will change once Microsoft roll out the service properly.
Users get 200MB of free storage, and the default backup schedule is once per day; the latter can be changed, however, though it will obviously impact on how much data is transferred. My Phone is expected to launch properly when Windows Mobile 6.5 is released.