At first I said that Sidewiki was cool, but simply that I did not think it was any threat to PR as we know it. Indeed I believe it creates more opportunities. Looking more closely, though, I now think that it is clever but I am not so sure that it is such a good idea. Here are ten and a half reasons why:
1. Users need to know it exists and website owners are not likely to put a button saying ”click here to see uninvited and possibly hostile comments on this site”
2. You need to install the toolbar to see it, at least for now.
3. You need to remember to turn the Sidewiki on.
4. Turning it on slows down page loading so you turn it off.
5. Controversial sites will block it.
6. Well managed sites will find ways to bury bad comments.