Below I have pasted a question/answer done by Craig who is the Director of Technology at Google:
Why in this day and age does Google continue to penalize sites that are virtual hosted? With IP addresses becoming harder to get/justify every day why does Google discount the relevance of links that don't come from a unique IP address. Please don't just deny it, I think the Internet community deserves an explanation.
I can't just deny it? What are my other choices? Actually, Google handles virtually hosted domains and their links just the same as domains on unique IP addresses. If your ISP does virtual hosting correctly, you'll never see a difference between the two cases. We do see a small percentage of ISPs every month that misconfigure their virtual hosting, which might account for this persistent misperception -- thanks for giving me the chance to dispel a myth!
We have no evidence of any other search engine treating a site better that has a Dedicated IP address. But being that Google covers 54% of the search engine market, we consider this enough to conclude that the others don't benefit sites with unique IP addresses as well.