First of all, Jack Layton has managed to get a meeting with Harper regarding environmental legislation. Harper knows that his Clean Air Act is dead in the water and that he is losing support regarding the environment, so talking to the NDP, which has had a practical environmental plan for a while now, to attempt to savage his environmental creditability, could be a smart move on his part, if he is willing to make concessions. As one should know, in a minority government, political parties need to negotiate agreements with each other.
Of course, it is very possible that Harper will not make any concessions at the meeting, which is why the NDP is already two steps ahead. Because the NDP is an effective opposition, it is proposing alternatives to what it is opposing; in this case, the NDP has introduced the Climate Change Accountability Act.
Finally, if the meeting goes really bad, the NDP has an ace up its sleeve, according to the CBC:
The NDP is expected to put a number of motions on the order paper Tuesday evening, including at least one no-confidence motion, NDP sources have told CBC News.I think that this could be a very smart move. If the confidence motion passes, it will be because of the Liberals, who would be unwilling to go to an election because of their lack of leader and direction. The NDP could then say that this is proof that the Liberals don't really care about the environment. If the government falls, then the election will be placed into an environmental framework, which benefits the NDP and puts the Conservatives at a distinct disadvantage.
The next day, the party is expected to announce which of those motions it will propose to the House on its opposition day. That choice will depend on the outcome of Harper's meeting with Layton, according to NDP sources.
The ability to negotiate, propose, and oppose are necessary in being an effective opposition, and it looks like the NDP is able to do all three. Maybe its time for an NDP government.