Given that I can think of many times I've wished I had my computer with me so that I could show someone a site that I had bookmarked at home, but now I have to wait to go home to email it to them, I can see an advantage of these social bookmarking sites.
But using these bookmarks to help "“less tech-savvy librarians have an equal voice in the collection,” instead of having one or two librarians editing a static web page."? Don't you have to be rather tech-savvy to feel comfortable using the bookmarks to begin with?
I don't particularly like Internet Explorer, and I much prefer my Firefox browser at home. Del.icio.us looks like it's intended to be used only with IE which I resent. What about people who are using older computers that don't work well with IE? What about people using linux to avoid the Microsoft issue altogether. Why is IE necessary?