Today's average for Yes Vote (15 September 2014): 4.03 (prev 4.19) 12 with odds reducing, one lengthing.
Today's average for No Vote (15 September 2014): 1.23 (prev 1.21).
Lowest odds for Yes Vote: 3.75 [11/4] (SkyBET).
Highest odds for No Vote: 1.25 [1/4] (UNIBET).
Summary: After the No vote drifted out for three days, it has come back in a bit. A typical bet for Yes is still somewhere between 1/4 and 1/5, with No between 100/3 and 3/1. The opinion polls are saying it's close, but the betting has not quite brought the two sides together.
A full analysis blog is here. The following defines the betting for a Yes Vote
The following defines the average bet for a Yes vote
The following defines trends over past 30 days