Since the abilities of a lot of existing bitmap formats aren't well suited for stupidly huge panoramas/gigapixel images or high dynamic range composites with 48-bit color depths, there's been development of new formats that pack better than jpeg, support deeper and wider color, and smarter tiling. As part of this Microsoft Research has released a really neat and free tool, Microsoft Image Composite Editor that allows you to output to some of these formats. Bottom line is that it does panorama stitching really well, and for free.
Since the resulting pictures were kind of huge, I uploaded two panoramas in the HD Photo, a.k.a. JPEG XR format. The viewer requires Silverlight.
Composite of Eagle Lage near Tahoe, California.
Composite of Emerald Bay at Lake Tahoe, California.
Below a plain old Flickr version: