If the answer to this is “yes”, Is Yahoo Shutting Down Del.icio.us? then if you are familiar with CURL, here’s how you can backup your bookmarks (from one of the comments in the post linked to above):
You can do a CURL on the command line: https://{your username}:{your password}@api.del.icio.us/v1/posts/all > bookmarks.xml to get the bookmarks as bookmarks.xml – then you can put them in a spreadsheet.