It seems that I wasn't quite up to speed in my post this morning - there is in fact a full-scale Scottish YouGov poll in today's Scotland on Sunday. Slightly infuriatingly, though, despite several minutes of searching the website I've failed to track down the exact figures, although from John Curtice's analysis it appears that the SNP are on 20%, and have been overtaken (but perhaps not by much) by the Liberal Democrats, while Labour have taken the biggest hit. So the SNP have indeed suffered a little from being completely shut out of what was by far the biggest setpiece event of the election campaign. Who'd have thunk it? If such an outcome had been achieved by fair means it might even be something for the three self-styled "main UK parties" to crow about.
I'm a bit dubious about John Curtice's suggestion that Alex Salmond should essentially swallow his pride and rethink his decision not to take part personally in two of the three Scottish side-debates. If there was the remotest chance that a good performance in those debates could achieve the same snowball effect that Nick Clegg managed on Thursday, I'm quite sure Salmond would be there in a trice - but sadly for us all no-one will be taking debates featuring Alistair Carmichael and David Mundell remotely seriously. The only way they could have less credibility would be if Iain "the Snarl" Gray was representing Labour. In any event, Angus Robertson is a fine debater, and although I expect the impact to be severely limited, I'm quite sure he'll be light-years ahead of the competition come Tuesday night.
UPDATE : I've finally tracked down the full figures at UK Polling Report, and it appears that my interpretation of Curtice's analysis was slightly wrong. The Lib Dems had only overtaken the SNP in the half of the sample that were questioned after the debate, but in the headline figures the SNP remain (at least for now) in second place.