I tested out Annozilla this evening. I could not get the sidebar going using the xul installer. Luckily, I saw the "Install Annozilla Sidebar" button in the viewing options on OS X and on Linux. This convenience was not mentioned in the installation doc.

Some very general notes:

While I have always had great hopes for web annotation, it is plagued by the classic chicken-egg problem. Getting the success feedback loop going involves building communities with web annotation. Applications will have to allow someone to easily locate and communicate with fellow annotators as they burrow through their favorite information piles.

I believe that certain communities are more suitable entry points for the annotation meme: bible study groups, classic literature students making use of the Gutenberg Project, the debate team / compulsive fact-hounds, and SEC filings consumers (that would include me).