We are loosely enforcing the one IP per account rule since using servers became popular. It is only allowed to use ONE (1) IP to access the site and multiple IPs to seed/leech.
Servers
You are not allowed to use the same IP to access the site on multiple accounts, but you are allowed to seed/leech from the same IP on multiple accounts. Basically, accessing the site in your browser from a shared IP is not acceptable, but using a shared IP to download and seed torrents is OK.