[spcmnspff]

Cheating through item drop mining with multiple accounts can't be done without paying for some in-game store item that makes the account a premium one, since free accounts can only be on the recieving end of a trade and have item restrictions (eg no hats).

If you mean the much more serious VAC-evasion by creating new accounts, they mentioned they would be cracking down on those, but no so sure about the specifics.