Totally agree with TropicalSun !
Imagine how easy it would be for Matt Cutts and the rest of those dogs to identify all those "SEO IPs" in order to kick all sites out of the SERPs ??
They just had to by buying a few hosting packages there... Google is also a registrar and DNS provider so they likely wouldn't even have to buy a package to identify the whole "spam IP range"....
It will cost more money and time to diversify your domains in terms of IP, DNS, Hosting, WHOIS data, etc but it will pay off big time in the long run !