There is no one definition of Governance. However, with regard to IT Service Management the adoption of ITIL and COBIT combined with certification against the ISO 20000 standard may be the closest we can get to be able to prove good governance.
Governance is in effect a representation of the personality of a company. Is the company open and honest or are they shabby and not particularly trustworthy?
Perhaps the most famous Governance framework of modern times is Sarbanes Oxley (or SOX). This is a USA framework that corporations have to abide by.