Ted Nelson on the invention of hypertext. And perhaps relevant to annotation today?
> But it seemed to me that as soon as you have computer storage you could put every point you wanted in - make the ones that are less relevant to your central topic, further away or allow the central topic to move as the reader proceeded. So, that notion of hypertext seemed to me immediately obvious because footnotes were already the ideas wriggling, struggling to get free, like a cat trying to get out of your arms. bbc
Interesting history of course. But it also answers a question people ask me -- how does the recent interest in annotation fit into the federated wiki vision? And the answer is this: annotation is the wriggling cat.
Textus Inclusus describes some old forms of annotation