Note that if the pool operator uses sendmany to send out payments, he'll probably only spend a small fee for everyone. In other words, he could probably send 0.01 btc to 12 different people in one transaction, and only spend 0.005 in transaction fees.
Take this transaction for example: http://blockexplorer.com/tx/f22f604f542d82f84b1bdb22ae01c09a4c5117596494b38562b96a6e71d81097
There are lots of tiny outputs in one transaction, yet only 0.005 in fees are spent because it's all one transaction.
But those are only processed by large pools out of good will and compassion towards poorer members of the BTC community, which is possible due to the (still relatively) low difficulty of creating new coins. That's not going to last forever.
Some hosts like Eligius already reject big transactions with low or zero fees. That will likely become more & more common in the upcoming months and years, esp. with bigger pools like slush/deepbit who have to pay for the bandwidth of free & near-free transfers of other people.