Google has a new blog post up with their recommendations for implementing infinite scrolling. Also be sure to check out the demo page.
Google’s tips and examples address SEO concerns with this feature, but don’t really address the possible user experience issues it introduces. As someone who is lucky enough to observe and work with actual users during usability testing, I’m not sure there is such a thing as a “good” infinite scrolling technique right now.
At least with this example the back button works as expected but I’m still not sure the positives outweigh the confusion infinite scrolling always seems to introduce. As with pretty much every UX issue, this of course depends depends on your audience and content. Like any other feature, get it in front of real users and test, test, test.