Sideloading application is one way people get non market based applications on their device; this feature was reported blocked on the Inspire4G, but that news has already been proven wrong by this video above. The demo was posted by one prerelease user that saw the news and just had to make a video showing how sideloading on that Android phone is done. Now this isnít how we are all used to doing it, and certainly AT&T didnít want this to be broadcasted, but this proves you can do it with a few steps.

Source (HTC Inspire 4G Allows Sideloading Apps, Doesn’t Advertise It | Android Phone Fans)