Windows Phone is one of the youngest mobile phone operating systems out there. Everything about Windows Phone is new and fresh, including its icon. Windows Mobile, the predecessor of Windows Phone OS was targeted at the business market rather than consumer market which is the chief focus area of Windows Phone. Its interface is new and its UI has a sense of fresh air. Here is how the Windows Phone 7 looks like:
Look how archaic Windows Mobile looks in comparison
Windows Phone 7 is indeed a fresh start. The new operating system makes use of live tiles. The home screen is much more lively.
People and artists have been very impressed with its overall design and have churned out several icon packs for it.
Download it from here. Here is another by the same developer. link
Icons mentioned above can be extremely useful the designers while designs the UI. Here are some more but by a different designer.
All of them are in PNG format and are transparent in nature.