The Overture program was never available to "regular" publishers... it was for people with a high amount of pageviews per month. I think it was something like 20 million. YPN is the only Adsense like program Yahoo has put out on a mass scale.
It's worth noting that entry requirements to Overture's program vary by country (for example the UK requirements are less than the US ones). Also even if you don't meet their stated page view equirements, it may be worth initialising contact if you are in a high paying niche, have a good brand and offer plenty of added value to the end user.
We were accepted a while back now, based on a mixture of volume, nature of traffic sources, future plans and the market we work in.
Having said that, you'd be wasting your time if you are very small.