Hmm, but I've had my fee set at 0.00 for quite a while now and haven't run into this issue before. Is there extra load on the system currently? Is there a way to cancel this transaction and redo it with a fee?
I wonder if a lower percentage of miners are willing to accept free transactions now. Or possibly the transaction load has been high, so even when someone taking free transactions mined a block, they had too many paid transactions. (By 'free', I mean those that have no transaction fee where one would normally be required, not including transactions using old coins that don't need a fee.)
Miners already have plenty of incentive to mine without fees being offered too, IMO, with the block rewards and all...
True, but they have very little incentive to include free transactions in their block. It can consume surprisingly large amounts of memory for the larger mining pools because they have to keep one copy of the transaction for each work unit they issue until a new block is found.
EDIT: Update: The transaction now has 3 confirmations.
Probably a combination of things happened. First, you might have got the transaction out to more of the network, getting around people who won't relay your transaction. Second, your coins may have aged a bit, increasing the priority of your transaction. Third, more blocks were mined, increasing the chance that a miner willing to include free transactions mined a block at a time when he couldn't fill it with paid or higher priority transactions.