We need a clickable visual representation for websites that is better than favicons and content thumbnails. Similarly to desktop applications world, this can simply be a big icon.
The clickable mockup highlights my secondary questions that I have not fully answered, but I believe it is possible to answer them.
How does the address bar work? For supertabs, it is unnecessary and a waste of space. I do not need to know the exact domain or URL for every page, since the supertab already clearly indicates where I am. I may want to copy the address to some external destination, though, which is why I can still display the addressbar or otherwise get the page URL when needed.
How does grouping work? The best I could come up with for the time being, is that supertabs act as containers that may have a number of pages under them. I currently represent them as subtabs. This is not ideal and would need more work. However, some amount of grouping is necessary to keep all pages from a supertab close to one another.
How does a site become a supertab in the first place? An obvious visual way would be by dragging and dropping from regular tabs area into supertabs. There may be other ways, but I didn’t explore this further in this mockup.
“SSL doesn't work, but how should websites authenticate themselves to users? Her solution is protected links: a set of secure bookmarks in protected browsers.” — which is exactly the point I was trying to make with Supertabs. Supertabs would be always visible, secure permanent bookmarks.
See also: “pinned applications” in Windows 7, and Chrome OS, both of which incorporate this concept.