This website uses polls to make predictions of seat totals for all Canadian elections.http://www.threehundredeight.blogspot.com/
There prediction based on the most recent poll show shows the Conservatives would win a bare majority of 57 seats if an election were held (need 54) with the Liberals getting 35 and the NDP 15. ( http://threehundredeight.blogspot.com/2011/06/pcs-on-track-for-slim-majority-in.html
). The Cons are 7 points ahead of the Libs.
Having said that, before the last election, the NDP was only around 15% in the polls federally. They ended with 31%. So it's not impossible for things to change markedly or for the Conservatives to lose a few points and thus, their majority. Such a happening could result in the NDP becoming kingmaker as they did in 1995, making Liberal leader David Peterson, premier. That time, NDP Leader Bob Rae promised to support the Liberals for two years on condition of Liberal action on certain social policy (the so-called Accord). Rae later regretted that he hadn't pushed for being partners in a full coalition. ( http://en.wikipedia.org/wiki/Bob_rae#1985_election_and_the_Liberal-NDP_Accord
Admittedly, I don't expect a 15% change in the electorate but a 10% move is not unusual. As it gets closer to election day, I think you will find that the Conservatives will fall in the polls and the Liberals and the NDP will gain. McGuinty was behind the PCs before the last election, too. The only really worry is that the Ontario electorate hasn't elected three back-to-back majorities for any party since the Conservatives pre-1985. But then Ontario hasn't picked the same party for Ontario that they have federally since 1985, except once, in 2003.