GACP means Google Analytics certified Partner
The Google Analytics Certified Partner Program provides an accreditation for people from companies that are engaged in web analytics, conversion optimization, website testing, etc. A number of companies are GACP and thus meet Google's stringent requirements in terms of working with, and deploying Google Analytics. Other benefits of a GACP is that beta versions of Google Analytics, the ability to act as a speaker at a Congress and the technical knowledge of the other partners. Read more about GACP on the Google website