Taking a broader look at the Cons' throne speech, I'd have to agree with the numerous other commentators who don't see it as likely that the Libs will vote down the Cons. But based on the most controversial measures the Cons have put forward, the reason for that likely support is based as much on the policies involved as the Libs' own calculation that they don't want an election.
After all, to the extent anybody has suggested an election trigger in the speech, it's the Cons' plan to put all of their most extreme crime measures into a single bill. But the Libs have already offered to fast-track the Cons' crime agenda, meaning that it wouldn't be anything new for them to back off again.
What about the War on Terror provisions which the Libs voted down? That was of course Lib legislation to begin with - and just a few months before suddenly rediscovering the value of civil liberties, they supported an extension of the same measures in committee.
The Libs got Canada into combat in Kandahar to begin with, and that position was extended to 2009 thanks to Lib votes. Stephane Dion is looking to give the Cons a run for their money in the tax cut department. And Dion said himself during the Lib leadership race that he didn't think he could get Canada to its Kyoto targets - which will make it awfully tough for him to bring down Harper for saying the same now.
In sum, a Lib party desperate to avoid an election indeed shouldn't have the least bit of trouble propping the Cons up on their throne speech. But that's largely because the Libs themselves have agreed with nearly everything the Cons had to say. And that makes it all the more clear that Dion and his party couldn't offer plausible opposition to the Cons even if they weren't distracted by their own internal meltdown.
Update: Alison has more.