Joel raises the concern that Microsoft's entry into the anti-spyware market would "wipe out a useful industry and replace it with something that's difficult to trust due to conflicts of interest," but I wouldn't be so worried about that. Microsoft's track record vis-a-vis viruses, spyware and sundry other nasties is so poor that no one would consider them the first choice in this space. Not to mention that Ad-aware and Spybot S&D are already free.