Microsoft CEO Steve Ballmer has unveiled the next generation of its Windows Mobile platform with the announcement of Windows Phone 7 Series out at the Mobile World Congress event in Barcelona.

With hardware not due out until "Holiday 2010" as Microsoft insists on calling it, it will be some time before you can see the OS for yourself, so this demo vid will give you a glimpse in the meantime.

Hit play to see the promo clip and let us know your thoughts on the new OS - which integrates Xbox LIVE and Zune - in the comments box below.