I can see some real value in using del.icio.us to build and add to a set of bookmarks with shared input and without the complications of copying & updating to everyone's computers. Gavin from Noosa Library has exported the Noosa Library bookmarks to del.icio.us so that reference staff at other libraries can use them and also add to them.
I am impressed with the National Library of Australia's AskNow Delicious cloud tag.
I have set up a del.icio.us account and bookmarked some of my favourite beading suppliers just to get the idea.