Since Iraq has gotten more attention than most places, it's easiest to assay general developments from what occurs there:
Greg Starr, Deputy Assistant Secretary for Countermeasures, Bureau of Diplomatic Security
Statement Before the House Government Reform Subcommittee on National Security, Emerging Threats, and International Relations
Washington, DC
June 13, 2006
2:00 p.m.
... The Department of State Diplomatic Mission in Iraq was reestablished in July 2004 ... Staffing for security programs in Iraq includes Diplomatic Security Special Agents, Marine Security Guards, third-country national local guards, hundreds of U.S. and Coalition troops protecting the International Zone and Regional Embassy Offices, and highly trained contract personal security specialists.
The security specialists in this latter category, referred to in the GAO report as Private Security Providers, have been critical to our efforts to create a secure environment for our U.S. mission personnel ...
http://www.state.gov/m/ds/rls/rm/67908.htm