Marcus Ranum has a new article up entitled "The Six Dumbest Ideas in Computer Security". I particularly agree with the first two, whitelists are the way to go. The six ideas, in my own words, are:

• Default Allow
• Listing and Blocking the Bad only (instead of listing and allowing the good only)
• Fixing security holes is software by trial and error
• Supporting hackers and hacking
• Educating users (this is a goodie)
• Early adopters