Microsoft have previously show Windows Phone 7 development on Expression Studio 3 however now they have now released a video showing Windows Phone 7 development on Expression Studio 4.

TechEd 2010 is currently on and Microsoft are currently showing off near final builds of Windows Phone 7. This latest video shows the OS is now running much more smoothly than the earlier build’s that were demo earlier this year. Jump to 2m:22s if you want to see the Windows Phone 7 demo.