Just as a slight corrective to the recent string of good polling results for the SNP, there's a new ICM poll which has the SNP a little behind Labour in the Scottish subsample: Labour 35%, SNP 33%, Conservatives 25%, Liberal Democrats 4%, Greens 3%. However, the potential error in an individual subsample is enormous, so those figures are very easily consistent with the SNP holding a small lead. That still appears to be where the balance of probabilities lie - there have now been eleven subsamples from various firms since the general election, of which six have put the SNP in the lead. Perhaps more to the point, the SNP have also been ahead of Labour in seven of the eleven subsamples.
That said, the battle between SNP and Labour seems to be close enough that it's not possible to say with absolute confidence which of the two parties is in front. The Tories have slipped out of that conversation, and it now looks increasingly likely that they've dropped to third place. If it gradually becomes an accepted fact that Scottish politics has reverted to a traditional SNP-Labour duel, what on earth will happen to the love affair between Colonel Ruth and the media, both north and south of the border? I believe the line is "she was the future, once".