Being jealous over Google's financial results (but who wouldn't?), Yahoo has decided to extend its online advertising network to small and medium size sites.

Initially, only sites from the US will have access to Yahoo Publisher Network, and another change Yahoo brought to its online advertising services is that from now on, Content Search will become automatic.

So far, Yahoo has accepted only large sizes and ads distributed through Content Search were placed only manually. With these changes, Yahoo becomes Google's main competitor. AdSense service, launched by Google in 2003, analyzes the content of a page and it automatically places ads according to the identified keywords.

Yahoo Publisher Network will accept for now, only a limited number of sites, approximately 2000, since it's still beta; new sites will be accepted towards the end of the year.

Yahoo will grant access to features like Add To My Yahoo and Y!Q, which will allow sites entered in the program to distribute the content on these channels.

In order to allow owners of the sites to comment and to announce the problems, Yahoo will create feedback forms and polls within Yahoo Publisher Network.