ISO/IEC 27001 has a formal title of "Information security management systems requirements specification". It is essentially a specification for an ISMS, and was formerly known as BS7799-2.
It is important to emphasize that this is NOT a code of practice, like ISO 17799. It is the certifiable standard within the suite of information security standards.
A transitional mechanism exists for those already certified under BS7799-2.
See also our register of
ISO 27001 Certifications
ISO 27001 mailing list
ISO 17799 Guide
risk treatment plan