The rulesets are now available in multiple versions on multiple engines. please visit http://rules.emergingthreats.net/ to browse all available files for the platform and engine you desire.
The open directory has the open Emerging Threats ruleset, the best of the old Community Ruleset (now defunct) and the best of the old Snort GPL sigs (sids 3464 and earlier) all combined using their original sids. Do not combine this ruleset with any other, you may have sid duplication.
The open-nogpl directory has ONLY the open Emerging Threats ruleset.
The blockrules directory has all of our dynamic IP list based rulesets for blocking known bad hosts.
The fwrules directory has all of our dynamic IP list based rulesets in firewall formats for blocking known bad hosts.