Does GOOGLE treat a web site located on a Virtual Site with less favour than that of a site on a unique IP address?

For example, if I host 20 web sites on one IP address and seperate them all by Host headers, and make sure no links are swapped between them and all text is unique to each site, would google punich me for the "virtual site" factor alone?

I have read many conflicting claims on the Internet regarding this and I would love to know for sure what Google's official stance is.