Most of the Fringe episode "Peter" is a flashback that takes place in 1985. To match the style of the era, location titles and the Fringe title sequence was given a new look. The Tron-style graphics are complimented by new "fringe science" subjects. While these subjects may have seemed "fringe" at the time of Back To The Future and Weird Science, every one (with the exception of cold fusion) is now considered mainstream science.
One thing that seems to be missing from this old school sequence is the "Observers Are Here" quote.
Screenshots of every frame from the title sequence are available at FringeFiles.com.