Interesting questions ...
Just as an immediate response to the original post: I presume you are already aware of the sitemenu module as in these examples?
http://www.nz-photo.com/
http://www.christophergrant.net/
http://neologisme.com/
http://www.carlosesteban.net/
The sitemenu allows a menu to build a basic site around the gallery, but as you most likely are aware, it doesn't provide the framework to actually display 'pages' inside the main stage. It only allows tooltips, popup windows, and links to external pages which you may build yourself. Optionally, as markam24 mentions, you can of course embed the gallery into a html page(or even a flash site).
As for the forthcoming stuff =), 'html' files will be supported, but initially only as a 'supported filetype'. That means that you can expect the content of a html to display(instead of a picture), but there will be no hokus pokus around it. Also, since flash only supports basic html text formatting tags, it will not be able to display complex html like tables or div tags.
After the initial release, we will sooner or later proceed with some further options for building the entire site around the gallery. Perhaps as an add-on module?