// This code can be removed after enough miners have upgraded to version 0.9.
// Until then, be safe when sending and require a fee if any output
// is less than CENT:
if (nMinFee < nBaseFee && mode == GMF_SEND)
{
    BOOST_FOREACH(const CTxOut& txout, tx.vout)
        if (txout.nValue < CENT)
            nMinFee = nBaseFee;
}

The above if clause was as below:

if (nMinFee < nBaseFee)

Gavin explains this change as:

Remove the rule that all outputs of free transactions must be greater than 0.01 XBT. Dust spam is now taken care of by making dusty outputs non-standard.

I don't see any other code change in the same commit. How is dust spam taken care of? Was it made non-standard in a previous version?