You'll see another thread here on chief delphi about a "quick way" to access the FIRST web site... but here is the ever-so-user-friendly, transparent and blatanly obvious (at least to FIRST's webmaster) to find picky little details like last year's rules...
Go to the FIRST website,
www.usfirst.org
Under the "Already Involved" heading, pick "FIRST Robotics Competition"
On the left side of the screen you will see "Documents and Updates", mouse over that and select "Competition Manual and Related Documents".
A page will pop up that will say "View Previous Year's Manuals and Documentation"
You should
end up here.
Jason
Edit: And all those answers were posted while I was typing this one. Wow.