You can also add that it's impossible to reach the site's footer where we expect to find the more detailed navigation elements of a site (like easy access to Contact, About, etc) and that it breaks the back button when designers make up their mind that you just scrolled through 10 'pages' on their site and updated the URL 10 times, so when you click back to escape their overloaded site to the site you came from, you have to click it 10 times to get there.
Reaching the footer could be solved by floating the footer and scrolling the text from behind it. This of course causes problems with having less space onscreen for the content you probably care about, but it is solvable.
Perhaps it could be designed to rise into view if you move the mouse cursor to the bottom of the screen, or in mobile application, perhaps it is visible when scrolling but after a predetermined timeout, it lowers out of view.
Another possibility would be for it to show when you scroll back in the list, like the address bar does with Chrome on Android. It is a little less discoverable, especially since the direction the footer would move is counter-intuitive to the scrolling movement, but once that behavior is seen the first time, I'm willing to bet that it is easily recognized and understood how to bring it up again in the future.
This isn't really a problem with infinite scrolling, but it may be a problem with the implementation.
