One day after the New Yorker published Jill Lepore's solid 'state of web archiving' essay, I may have witnessed the future of web archiving. The lesson here is that the field has a history, and is constantly moving. The future of website preservation has yet to be written.
Lepore's narrative rightly places Internet Archive (and both its Wayback and Heretrix programs, as well as Archive-It) firmly at the center of current efforts to back up web pages. Internet Archive has become even more central to web archiving after merging with the largest alternative service, the California Digital Library's Web Archiving Service.
Maybe I shouldn't overstate the importance or revolutionary nature of pywb. After all, Kreymer has worked for Internet Archive, and the python version may draw strongly off of Wayback. But my observation is that even as we have a sophisticated review of the state of web archiving (Lepore's essay), the landscape can rapidly change. To Lepore's credit, she really does capture the cutting edge - Perma.cc, plus Memento and it's 'time machine' aspirations, are mentioned - but pywb may be the bleeding edge.
Web archiving and link preservation even have a longer history. Lepore could have reached back further to discuss persistent URLs, the Handle system, or the GPO web harvest pilot of '06. I'd love to dig into this history even further some day - please contact me if you'd like to work with me on it!