Government Jobs
Federal
The federal government is the single biggest employer of lawyers in the U.S.. Many jobs are located in Washington., D.C., with many field offices around the U.S. Federal government jobs are searchable: 
http://www.usajobs.gov/.
For those wishing to stay in California, here are listings for possible public law and policy employment in the federal government:
Executive departments - all hire attorneys, many through entry-level Honors Programs run by each department. The Department of Justice has Honors Programs for attorneys and law students: http://www.usdoj.gov/oarm/arm/hp/hp.htm.
Other examples: Commerce, Education, Homeland Security; Housing and Urban Development, Interior, Labor, Transportation, Treasury, CIA, FBI, IRS
Administrative agencies - all hire attorneys, most through entry-level Honors Programs run by each agency.
Examples: Environmental Protection Agency; Equal Employment Opportunity Commission, Federal Trade Commission, Securities and Exchange Commission
Legislative offices/aides
Staffer to House Member or Senator
Staffer to legislative committee
Congressional Research Service
Office of Comptroller General
Courts
Judicial law clerk
Research Attorney
Court Administrator
State
The state is the single biggest employer of lawyers in Sacramento. Many externships provide experience in these jobs. Most jobs will have alumni contacts. Being hired requires taking a test and being placed on a list. California state jobs are searchable: http://www.spb.ca.gov/index.htm?e=1.
For possible state government employment, including city and county agencies, see the attached listings:
Executive agencies - many take externs and hire attorneys.
Examples: Attorney General's Office (specialized criminal and civil departments); Department of Education; Environmental Protection Agency; Fair Political Practices Commission; Food and Agriculture; Health and Human Services; Homeland Security
Administrative agencies
Examples: Air Resources Board, California Energy Commission, California Coastal State Lands Commission.
Legislature
Staffer to House Member or Senator
Staffer to a legislative committee
Legislative Counsel's Office
Courts
Judicial law clerk
Research Attorney
Court Administrator
Cities/Special Districts:
Cities hire municipal lawyers to advise local government officers and departments. Some municipal lawyers do transactional work. Some do litigation. In addition to local municipal governments, special purpose, limited, government entities are common. Examples include school districts and utilities districts.
District Attorney's Office - criminal law, prosecution
Public Defender's Office - criminal law, defense
City Attorney's or County Counsel's Office - advisory, litigation
Specialized municipal agencies - e.g., school districts, utilities districts - staff attorney positions