believe me, you have to give this new version a whirl, especially if you do any sort of collaborative work or if you blog or if you’re a researcher.
For a great overview, see Social Bookmarking 2.0 — Diigo sets the standard for others to follow (bub.licio.us). That entry gives you the nuts-and-bolts of what Diigo does.
An aspect I really appreciate (which isn’t stressed in the bub.licio.us article) is the control users have over whether or not to make a bookmark public, keep it private, or share it with others to a group. Another great feature is that users can make their annotations (the “sticky” notes) public, private, or shared to a group — and these settings are easy to change within a single bookmark, too.
Diigo is quite simply fantastic! Congratulations to the whole team for bringing this to the web.