The ISO20000 Standard
In a nutshell this is the international standard fir ITSM (IT Service management). It's publication, in 2005, was a hugely significant development, as it is certainly going to become a major influence on the ITSM landscape.
ISO20000 comprises two documents:
Information technology - Service management - Specification
Information technology - Service management - Code of practice
It is the former of these two against which formal, organizational, certification is available. Again, the existance of a certification route for the enterprise is a major driver, as it potnetially acts as a market differentiator.
As with many international standards, the ISO documents are in fact based upon earlier publications by BSI. In this case, the original ITSM standards were BS15000-1 and BS15000-2.