Quote Originally Posted by Ruperto
I know some people claim that a shared IP doesn't make a difference, but I'm from the old school in SEO and have always made sure to get a host that allows me to have a unique IP for each domain. "Old school" meaning that I've personally seen entire block C's banned due to one bad apple (a spamming webmaster with an IP in the same block C).
If you are on a large enough Host, have them split your addresses into multiple C Blocks.

If you can’t split your addresses, get another Host.

SEs are not immune to mistakes and multiple RE sites within one C Block can create problems regardless of how innocent you are. Especially if they are cross linked.

Better safe, than sorry IMHO.

-Mack