I've been doing a lot of 360x180 degree images lately for websites. I'm using a 360Precision pano head (sweet!), D70, and a 10.5DX lens. I've gone through the whole search for the perfect software that does everything perfectly, with no input from me, and in record time, but I haven't found that piece of software yet.
Someone mentioned Hugins in this thread before, and it is what I've settled on. It is much like PTGui and PTassembler, but it is open source and free. Only lacking for me is that ability to apply a template to each project, which would speed up stitching of multiple exposures to later combine to increase dynamic range.
Also, I had a few questions about what I use from visitors to my website, and my father wanted to learn how to do this also, so I wrote a couple page article and posted it at my site. Hopefully, it explains a bit more about Hugin, autopano, and enblend.
As a side note, Autostitch seems just to be using the SIFT method of finding control points, which is exactly the same as autopano and autopano-SIFT both of which are free and usable inside of Hugins. With Autopano, enblend, and Hugins ability to output .tiffs, etc... it would seem that users of Autostitch would benefit from the switch to the free and open source Hugins.
Anyway, at this point with Hugins, it takes me about five to ten minutes to stitch a 360x180 image made from 8 level pictures, one up, and two down. Then using the photoshop 16 bit plug-in for PTtools, I add in the nadir point. This adds about 15 minutes.
Hope this helps,
Here's the link to the article:Quick and Dirty Hugin Panoramic Stitching