Magistrate Judge Improvement Act of 2000 - Amends the Federal judicial code to revise magistrate judge contempt authority, allowing such a judge to use such authority to: (1) punish summarily by fine or imprisonment in cases of obstruction in the administration of justice; (2) punish by fine or imprisonment in cases involving the consent of both parties to such proceedings and in criminal misdemeanor cases; and (3) provide civil sanctions in such consent cases and cases involving misdemeanors.

Provides the process for certification of the facts of a contempt ruling to a district judge for execution (including appeals) of punishment or sanctions.

Amends the Federal criminal code to provide magistrate judge authority in cases involving petty offenses and petty cases involving juveniles.