This is a difficult week for social software systems!
Typepad, one of the blogging tool from Six Apart , was down for several hours on Friday (approx 15-20 hrs)
Now, it is the turn of Del.icio.us, the social bookmarking manager, that just got bought by Yahoo!
Del.icio.us has been down since 8pm PST yesterday and was back online early today.
More info on the Del.icio.us blog