The ability to prorogue parliament has always been a procedural tool that has always been available to the Government. It is an opportunity for the Government to reset their agenda without calling an election. Last year Prime Minister Harper used it to postpone a confidence vote that threatened to topple the Government that had been elected 6 weeks earlier.
Harper has once again used the tool of prorogation to extend the Parliamentary break until March. The thrown speech will be on March 3rd, immediatly followed by the budget on the 4th. The current break had been scheduled to end on January 25th.
Opposition parties and critics are upset that Harper is once again playing the "take the ball and go home" strategy. He is trying to delay the hearings on the Afghan detainee issues to avoid the truth from coming out. This issue isn't hurting the Conservatives in the polls. It would hardly enough of a reason to prorogue Parliament. There are more important motivations in this decision.
The most obvious reason is the Olympics. No party wants Parliament to be sitting during the Olympics. If anything of importance happens it would either be overshadowed by the Olympics or attract negative attention from the entire world. This is why if you wish to draw attention to a particular cause to be addressed by the Government you don't hold a press conference when Parliament is in session. It is too risky that your issue is overshadowed by a big news day in the Legislature. The focus during the Olympics should be about sports and promoting Canada. Politics can take a back seat for two weeks.
From a strategy point of view the most important reason to Prorogue Parliament comes from the Senate. The Prime Minister in a position to appoint 5 new Senators. This will shift the standings in the Senate to Conservatives 51, Liberals 49. Factoring in the two Progressive Conservative Senators they will have a majority in the 105 seat Senate. For the first time Harper will have minimal concern about the Senate blocking legislation. Prorogation or an election are the only ways to adjust the committees to reflect the new majority. Without the changes they would have an easier time stalling or stopping legislation.
Unfortunately politics is often more about strategy than substance. Harper is taking advantage of an opportunity to improve his ability to do what he was elected to do; Govern. He would not be doing his job if he missed out on this oppurtunity. If the Opposition parties don't like it they can take down the Government on the budget. In the mean time Harper is demonstrating he is a master strategist. He may have a minority Government but his hold on his job is as solid as any other majority government.