The Washington Post is wrong. Today's Post says that the grand jury has to unanimously agree to return indictments. HuffPo readers have known since last week that it takes only a majority of grand jurors to indict--12 of 23.
Experienced federal prosecutors are saying today that they expect Fitzgerald to extend the term of the grand jury even if he obtains indictments this week. Prosecutors sometimes go back to grand juries a few weeks after indictments to ask them to supercede those idictments with additional counts. This happens when the original indictments put pressure on witnesses to give up more information or when defendents decide to turn on each other and give the prosecutor more information during plea bargaining.