Both Google AdSense and Yahoo Publisher Network publishers are reporting getting payment early this month. Some suspect it is due to being closed during the normal pay period, due to the holidays. Some suspect Google and Yahoo are being nice for the holiday season. Some suspect it might have to do with making sure payment goes out before the end of their fiscal years (due they even go by the calendar year?).
We have a Google AdSense related thread at WebmasterWorld where many have reported already receiving the money in their bank accounts. We also have a Yahoo Publisher Network related thread at DigitalPoint Forums.
For whatever reason the payments are going out now, many publishers are finding it to be a nice holiday gift.