As we've heard, the interface appears to be pen-based and centered around drawing and writing, with built-in handwriting recognition and a corresponding web site that allows access to everything entered into the device in a blog-like format complete with comments. We're also hearing that there will be a built-in camera, and there's a headphone jack for media playback. Most interestingly, it looks like the Courier will also serve as Microsoft's e-book device, with a dedicated ecosystem centered around reading. It all sounds spectacular, but all we have for a launch date is "Q3 / Q4", and we have no idea how much it's going to cost, so we're trying to maintain a healthy skepticism until any of this gets official -- call us any time, Microsoft. One more pic showing the interface after the break.
Update: We've added a gallery of user interface shots -- some of which we've seen and some of which are new.
Update 2: We've just gotten two full-length HD videos of the interface in action. We've seen parts of these before, but there's some new stuff here that's quite interesting. Check it below.