I was reading on a techie forum that was just a myth.
1000 diff IPs for 1000 diff domains has the same effect on Google PR as 1000 domains on avirtual account sharing 1 IP address. Assuming the host has the server and accounts configured correctly.
Otherwise, the millions and millions of web sites on shared hosting accounts would all be considered only a few diff sites (since thousands share a single IP), and that assumption would be just silly.
http://www.mattcutts.com/blog/myth-b...-ip-addresses/