I’ve been invited to participate in the beta for the nascent Yahoo! Publisher Network, so those of you who read this on the site will see the YPN ads to the right. (They seem to get cut off a bit in Firefox, at least, so need to work on the formatting.) The most interesting thing, thus far, is that you have the option of choose what categories of ads appear on your site, so categories are taken into account as well as (or maybe instead of) the context of the page. I chose the professional services/advertising-marketing category, but so far only ads for lowermybills.com and Vonage are showing up. They did say it might take a while. One other thing I found different from Google — if you’re both a YPN publisher and a YSM advertiser, you can take your publisher earnings and transfer them directly into your advertiser account.
I’ll keep you posted if I learn more as things go on.