The ability to use your Windows Phone as a mobile hotspot was originally an exclusive feature extended only to brand new Mango devices, but we're now beginning to see Internet Sharing pop up on the HTC HD7 and Mozart. We're seeing reports that it's showing up in various parts of the world, though we still haven't heard if this will include T-Mobile HD7 users in the US or if it still awaits final carrier approval first. Either way, it's probably worth clicking on that Zune icon to check for the update.
[Thanks t