Not sure what you mean. Google releases new algorithm updates just about daily. Every so often, there are some big ones that happen, but Google doesn't release official announcements about them. The SEO community finds out because people begin to notice large shifts in their traffic overnight and so they announce it and get confirmation from others experiencing the same thing at the same time.
google has recently updated google panda and google pengiun which bans useless sites and effect ranking..
in response to ur question there is no such officail site of google where it updates its new rules..
only the seo or experience webmasters reaserch and get to knw abt latest updates which r furtur convey to other webmasters.