From MLB.com:

Chuck Knoblauch has agreed to give testimony to the House Oversight and Government Reform Committee both privately and later at a public hearing on Feb. 13, the two Congressional leaders of that committee said in a joint statement released on Monday.

Knoblauch, whose deposition or taped interview had been scheduled for Tuesday, has had it postponed for the second time and is now rescheduled for Saturday.

The subpoena against him was withdraw due to the fact that he is now testifying "voluntarily".