Google is providing its users with dual layer protection by means of a 2 step verification.This method requires you to type in a special code in addition to your password.Learn more about 2 step verification and the step by step setup process at c-madeeasy.blogspot.com/2011/11/what-is-google-2-step-verification-and.html
This may help: http://www.google.com/support/accounts/bin/static.py?page=guide.cs&guide=1056283&topic=1056285
In simple words - it's about using two passwords. One that you have remembered and other sent to your phone. Setup your phone at this page.
Enter your mobile phone number, then you will get a verification number. after that enter the verification, if true, then each time you login, you will get a verification to your mobile phone first. This is the safest way for your account, you will not see on other sites with facilities like this.