What I have right now is a single-column page with Paul Irish's Infinite Scroll serving up new content. After scrolling to the bottom, however, the script will often attempt to continue loading new pages when none exist. The script should print an error message when no new content can be served, usually triggered by a 404. From his FAQ:
Does it still keep going, even at the end of the blog?
Infinite scroll is configured to die when it hits a 404 Not Found status code, so when it goes through all your archives it should hit a /page/43/ (or something) that doesn’t exist, then show a message “Congrats, you’ve reached the end of the internet.” Some wordpress themes don’t report not found pages with a 404. Try a different theme or contacting the theme author.
As far as I can tell tumblr serves a blank page instead of a 404. Is there any way to alter this behavior so that Infinite Scroll stops properly?