It has to be said that at this point, without an election actually called, any poll is suspect. People are not actually facing that ballot sheet. They might be willing to say anything. Of course, this is true during the election campaign too, but I think the seriousness with regards to polls goes up a notch. But remember that everything changes when you've got that pencil in your hand.
That having been said, it would seem amazing that the Liberals are doing as well as they are. The "scary" Conservatives message seems to be working. But I think it's more than that. The Liberal numbers are high as a result of extraordinary effort. The Conservative numbers are low and they haven't even started yet.
What I mean by that is this: we've seen the Liberals put the Prime Minister on TV in an unprecedented broadcast, make a widely reported $4.6 billion dollar with the NDP, and then proceed to start making something like $6 billion (and counting) in program announcements. For all that, they've clawed back to 30%.
The Conservatives have done little, really. Or little that has been reported by the main-stream media (and this will probably be a problem in the election that is to come). Part of this is that, not being the government, they can do little except talk. Part is because they are keeping their powder dry until the election campaign starts in earnest. And part is that they will need to shape a message that says more than "The Liberals are corrupt!".
But despite this, they are at 33%, ahead of the Liberals and just beyond the margin of error for the poll.
Meanwhile the hard-left vote is being split by the NDP (17%) and the Green Party (5%). It will be interesting to see if the near-left NDPers (union workers, for example) go to the Liberals again in this election, or if the corruption (and revelations still to come) keep them with the NDP. Of course, disgust that the NDP would make a deal with the Liberals might keep some of them at home. Similarly, it will be interesting to see if the Greens can captialize on exactly that distaste with dealing with the Liberals to draw some of the far-left (single-issue environmentalist voters, for example) into their camp. But then that has to be balanced against the vote-splitting that will help the Conservatives in some ridings.
So unless the Liberals can somehow maintain this superhuman effort (and at some point they'll run out of money, if not chutzpah), this might represent a high-water mark for them. Similarly, once the Conservatives finish crafting their message and get fully engaged, their numbers might start to move up again -- in other words, this represents their starting point.
The Liberal's best hope? In my opinion, scaring the NDP-Green vote (again) into voting for them, though the dynamics between these parties are somewhat different this time around. It'll be fascinating to watch these numbers move.
[Update: The Amazing Wonderdog points out some flaws in the original data presented, but I stand by my suggestion that the surge the Liberals have experienced is more to do with the unsustainable effort expended this last week.]