I have applied to the Yahoo publisher network with a couple different sites and they always eventually send back a little "Thanks your your request, we'll let you know when we are ready to let you in."

I hear good things about Yahoo and I want in.

Same here! I want to get in, I heard its much better than Adsense

First off, you need to live inside the USA.
I got in pretty easily, but it helps if your site gets a good amount of traffic.

Will it be opened to non USA residents once its out of beta?

I hope yahoo is better than adsense, I dont like adsense very much. I am trying to get in!