Update: This version of the plugin has been superseded by version 0.2
Right now setting up my Delicious plugin isn’t the easiest thing in the world - so here are some illustrated step-by-step instructions!
Download and unzip the plugin (Available here)
Copy the plugin file to the right directory. This will be /Users/your_user_name/Library/Application Support/Google/Quick Search Box/PlugIns
Copy the plist file to the right directory. This will be /Users/your_user_name/Library/Application Support/Google/Quick Search Box
Open the plist file with TextEdit. Put in your Delicious username and password and save your changes.
Restart Google Quick Search Box and verify that the Delicious plugin is listed. Under the S column (for ‘Sources’ I think) there should be a 1.
Make sure that Delicious Bookmarks are selected as a searchable item.
If all has gone well, your Delicious bookmarks and tags should show up as search results.
You can pivot on tags to narrow the results to just those bookmarks with the given tag.