The Yahoo Publisher Network has made a series of changes to their interface and support documents which seem to be appealing to the new publishers. They have also added a new "RPC" column to reporting, meaning publishers can see their average earning per click.
Lastly, they have increased the payment time from 25 days to 27 days, although it is unclear if it is a permanent change or if it is only to accomodate the weekend.
I also was fortunate to interview Cody Simms, the YPN product manager behind all the updates on my radio show Click This! You can download the MP3 here if you would like to listen Cody detail the changes and the decisions behind making them.