The preceding is a Sidewiki entry I entered on Google's intro Sidewiki page. I'm wondering how useful it will be. It's likely that pages will just be filled with comments that I won't be interested in. But if I can search for comments by particular people, that might be useful.
It's also interesting that Google's computing power seems to be growing much faster than the web itself. Google must store all these entries in its computers. It's an interesting way for Google to know what pages people are looking at.