Here's a posting from the download squad which allows you to search your del.icio.us bookmarks through spotlight. It seems quite integrated as a search for "palm" on my computer now reveals 46 entries under Bookmarks! Very simple to use and logs in when you boot up your mac. Combined with the del.icio.us firefox plugin and this spotlight plugin I no longer need to visit del.icio.us again (unless I'm on my XP machine).
I found this article originally from the TUAW here
The Download Squad article is here
And "delimport" is here