lammert - 2:44 am on Feb 2, 2010 (gmt 0)
There is no need for a NAT to share one IP with multiple websites. Name based hosting in the HTTP protocol was one of the first attempts to combine many websites on one IP address to reduce the number of allocated IP addresses. Unfortunately the SEO community decided that a separate IP per site might have some benefits. Nowadays many webmasters are even willing to pay a monthly for a unique IP address.