Reserve Bank of INDIA (RBI) has made PIN mandatory for online credit card or debit card payments. 

• PIN is in addition to other information we provide like Card No., Name, Expiry Date & CVV no.
• Since it is a notice issued by RBI it is applicable to cards issued in India only. If your card is issued from any other country it will have a normal authorization process.

So this comes into effect from August 1^st, 2009.