On July 28, 2011 Google announced PageSpeed Service, an online service to automatically speed up web pages is coming to an end on 3rd August 2015. In the last 4½ years, PSS has delivered millions of pages for thousands of sites, all for free. While a number of sites continue to enjoy the benefits of PageSpeed Service, we see much broader adoption of PageSpeed technology through our open-source products and have therefore decided to focus our efforts on improving those. Users must change their DNS to point away from the service by this time, or their sites will cease to function. Google has created a migration page that includes assistance for changing DNS as well as information on other ways PageSpeed technology can be employed on websites. Please see this article for more infromation.
At the same time Google is also announcing the deprecation of PageSpeed integration with Google App Engine. If you are using PageSpeed integration on Google App Engine, it will continue to function until 1st December 2015, after which PageSpeed optimizations will no-longer be applied to your app. No action is required on the part of App Engine users; after this date apps will continue to operate, except without the benefit of the PageSpeed optimisations.
The open source PageSpeed server modules mod_pagespeed and ngx_pagespeed and the PageSpeed Optimization Libraries are unaffected by this announcement and development on these will continue.