Well, I think it's a definate must to be more demanding when it comes to dedicated IPs, especially with the increased level of spam, phishing, etc.

Dedicated IPs open quite a few doors for online criminals. For this reason alone, I think increased demand for justification is...well....justified.

Keep in mind however, that I have never had an instance, or even heard of one, in which an allotment of IPs were denied by a datacenter or ARIN.

Dedicated IPs do come into play however, when it comes to spam and blacklisting. For example, some blacklists don't stop at the mail server. They also dig info on the sending domain to retrieve the IP of the domain sending the mail. They then blacklist the IP, and in most cases, the domain too.

LayeredTech (www.layeredtech.com) are pretty tough on assigning IP's to you. They follow the ARIN stuff to the letter pretty much.

For most people it isn't a problem, but, for those with the 'IP per site for SEO' idea it can cause problems - as ARIN don't really accept that as good justification

ARIN can audit dc's IP records at any time - and the DC's themselves need to show ARIN they are using their ips (and how they are using them) before they can get further IP's from them. Fits in logically the DC's would then adhere to the policy.

I've heard of an instance where ARIN have denied allocating them a larger allocation then they needed so the company went for a /21 block instead of a /20.

I'm not sure why SEO people need multiple IP's. I've never even seen any proof that different class-C ip's even work to their advantage. Heck, I've always heard that the IP's are worthless for SEO.