Norman Spector and Geoffrey Stevens offer some perspective at globeandmail.com.

From Spector's blog, in a post entitled Pollsters were among the losers in the 2008 election:

Never before has been there so much public polling in a Canadian election. And, aside from the volume, never before have there been so many nightly tracking polls presented to the public.

Before we close the books on a fascinating campaign, therefore, let it be noted that, with but two exceptions, every pollster blew the 2008 election. True, no one called the Conservatives to lose. However, most under-estimated Conservative support by more than the margin of error in their sample size. The two exceptions were Angus Reid and Leger Marketing. Most other pollsters had the Conservatives at 34 per cent or less in their final polls.

As Stephen Harper noted in an election interview, he has learned from his mistakes in every election. And all the political parties are now conducting post-mortems on what they did well, and what they did not so well in 2008.

One would hope that pollsters, too, are reflecting on their work. As should be journalists and editors and media executives, who made such copious use of polls during the 2008 campaign.'

Now, why might the polls have gotten things wrong?

Winsor had the following to say in an Oct. 21 column:

There has been an ongoing debate about whether polls influence citizens' attitudes and votes, or merely reflect their attitudes and voting intentions at a point in time. The knock on the pollsters is that their snapshots have one of two possible effects: They either encourage voters to get on the winning side, as telegraphed by the polls, or they encourage strategic voting to prevent an outcome that is being indicated by the polls.

The best recent example of the latter is what happened in the final days of the 2004 federal campaign in Ontario, where NDP supporters - concerned about a potential victory for Stephen Harper's Conservatives - moved substantially to the Liberals. The same shift happened again in 2006 to a lesser extent, holding Mr. Harper to a minority.

To the extent that bandwagon effect or strategic voting are deemed bad, there is a concomitant increase in the public's resentment toward pollsters. These critics argue they shift attention away from policy and leadership issues toward the "horse race."

In 2008, this resentment was particularly evident among Liberal supporters and especially Liberal campaign organizers, who felt the proliferation of polls (we had three conventional daily tracking polls and another daily survey which concentrated on potential swing ridings) smothered their attempts to focus on issues, especially the environment.

In Ontario this time, the numbers would suggest the polls had an influence on strategic voting - but to reduce its prevalence, not increase it. This contrarian switch may also explain why the main tracking polls captured the national vote intentions within their margins, but offered a misleading picture in Ontario. ...

Mr. Nanos (Nik, of Nanos Research) says two things happened over Thanksgiving. The surveys indicated Ontario voters were more concerned about the economy than voters in other areas - so in Ontario, the economy became the ballot question. "Whether or not people liked Stephen Harper, he was competitively a better choice to manage the economy than Stephane Dion."

The second development was more tied to polling. Because the polls detected the Conservatives' precipitous decline in Quebec, it became conventional wisdom that Mr. Harper could not win a majority; hence a decline in the widely held apprehension about handing the Conservatives full control.

Nanos makes the point in Winsor's column that Canadians aren't particularly loyal partisans and many are last-minute political shoppers.

I work for CTV News. The Strategic Counsel did polling throughout the campaign for CTV and The Globe and Mail.

Its final poll, published on Oct. 12, was based on sampling conducted on Oct. 11. Two thousand people were sampled, resulting in a margin of error of plus or minus 2.2 percentage points 19 times out of 20.

It had the Conservatives at 33 per cent, the Liberals at 28 per cent, the NDP at 18 per cent and the Greens at 11 per cent.

As it was, the Tories finished with 38 per cent of the vote, the Libs with 26 per cent, the NDP at 18per cent and the Greens with seven per cent.

It would be interesting to conduct an election-day poll to see whether that result fell within the margin of error when compared to the actual election results.

But clearly the wind had slowly been coming back into the Tories' sails over the final few days.

I don't think you can say the Strategic Counsel poll was inaccurate, but I also think it's wrong to assign predictive value to it. Much can happen in the three days before the polls close.