No, the IPs are all different. It seems to be a bunch of individuals submitting their own blogs. What's odd is they happened all at once.
A very good question actually. How distributed is a spamming user base ? If it's just one IP, it might be a work of a drone from a marketing department.
Might also be worth checking the IPs see if they are listed in Spamhaus block list. If they are, then pretty good bet its organized spam.