Today's Scottish subsample figures from YouGov are : SNP 48%, Labour 20%, Conservatives 18%, Greens 5%, UKIP 4%, Liberal Democrats 3%. That's happened in spite of a whopping downweighting of respondents who identify most closely with the SNP - they've been scaled down from 52 to 30.
Individual subsamples are of course not especially reliable guides to the state of play, but there has been a particularly high concentration of this type of finding over the last few days. It wouldn't be entirely surprising if the SNP lead is indeed hardening still further, because the Tories' tactics of portraying Alex Salmond as a potential master of the universe after the election is playing into our hands rather nicely. They obviously don't particularly care that it's playing into our hands, because they're speaking almost exclusively to an English audience, they don't have much to lose in Scotland, and all the tedious rhetoric about their "undying love for our glorious United Kingdom" is a load of guff.
For those who are concerned that the SNP should be downplaying expectations much more than they've been doing, it's worth bearing in mind that this very beneficial hype in the London media about the filthy Tartan Hordes would probably not be occurring if expectations hadn't been ramped up to the max in recent months. There may be a careful balance that needs to be struck between canniness and swagger over the days and weeks to come.