Yahoo is developing a search engine with which you can get the search results from past. Its just going back in the past and searching yahoo again. Things can be interseting as well as funny if you will search different speculations and innovations and can see what people thought about it at that time.
For example if you search about Obama and click on the year 1998 you will get very few results and may see insignificant articles about the person.
Have a look … Visit temporary URL
But how it is giving search results about the future?
Actually it is fetching the results of present in which future has been described. For example if you search about 2030, it will show all results where it is said about the year 2030.