Is there any code that you can place on your website that can tell YPN the theme of your website? I know that adense offers this, and I wanted to know if this can be done with YPN.
you can't do it with adsense. you can't do it with y!pn either. you can select the themed ads via Y!PN, but you can't 'tell' it your theme. It's either contextual or selected (Y!PN).
If you go to http://www.google.com/support/adsense/bin/answer.py?answer=23168&topic=371 you can see that you can help adsense target the theme of your website.
You cant do it by placing code on your website, however YPN as categoary targeting which you can do by loging into your YPN account
Does anyone know what YPN scans on the webpage to determine the web page theme? Does it look for some sections over other sections?
No right now thats one of the problems they are working on.There is no one straight answer yet. But i know for me, keywords on the title and title page help a lot.