From Smart Tags to Blerp, how did third party annotation become cool?

In 2001 nearly everyone hated Microsoft’s Smart Tags.
You may recall that Smart Tags were a failed IE feature for adding annotations to websites.
Eight years later, why is everyone now fascinated by Blerp, which sounds like Smart Tags with a cuter, Web 2.0 name?
I did send an email to Blerp pointing out the 2001 A List [...]