I'm an absolute beginner at this - I just installed the system for the first time this morning. But I did add the gallery widget - instead of putting the folder 'gallery' inside mysite, I put it at the top level (same level as 'mysite'). When I ran the db/build it did appear to add it correctly. When I create a new page, I can see the 'Gallery Page' as an option in the pulldown list.
Thanks but unfortunately did not help - I did notice that the /db/build did indeed return information to the page when the gallery folder was at the top of the directory structure, but still no additional page in the admin. I'll keep plugging away -