what i found out is the intimation the stanford search powered by google.
so the people behind it had the big plans way before the paper was presented.
other might be:
go button which is missing in google main page.
the left hand side bar
copyright complaints (they may have overshoot their limits and hurt someone)
Goody!!
interestingly this feature is already present on scholar.google.com
In fact, there it works better than the same feature on publisher websites.
eg if u go to ieee.org and search for papers then the date mentioned in search is the date they were added to the electronic db, whereas google correctly list all papers as per publication date.