Matt Cutts of Google busted a myth regarding to dedicated IP address for websites. No, your website will not be penalised, nor rewarded, for being on a named-based virtual hosting, or on its own dedicated IP address.

Links to virtually hosted domains are treated the same as links to domains on dedicated IP addresses.

Funny that when you go and shop for dedicated servers or even VPS, you’ll find providers giving you “unlimited IP addresses” as long as you can justify it. What are other reasons people need more than one IP addresses for their web servers?

• HTTPS. As SSL certificate is transmitted before HTTP transaction starts, you can’t send back different certificates depending on name-based virtual hosting.
• Blacklisting. Maybe not Google, but other search engines. What if another site on the same IP is blocked the countries with censorship, like China? Will your site be affected?
• Ethics. If you are running a church website, you don’t want to be seen on the same IP address as pr0n sites and poker sites, do you? Nor do you want to be seen hosted on the same server as spammers/phishers, do you?

Anything else? Otherwise for SEO purpose there’s no reason to “waste” IP addresses by having a dedicated one for your site. It’s always amazed me that a defunct company like DEC has its own class A network, where many Internet users in Asia are forced to sit behind NAT as their ISPs do not have enough IP addresses allocated to them.