LMH (an unidentified hacker) and Kevin Finisterre have started publishing a new Apple bug each day this month (January 2007) in order to bring attention to that fact that Apple software has security bugs too. This is similar to a browser bug a day that H D did in July of 2006. H D did give the vendors advanced warning before releasing each vulnerability, though LMH and Kevin Finisterrre will not.
I believe if Apple really wants us to switch to their platform, some proof that they know how to deal with security issues is important. It will be interesting to see how Apple responds. LMH and Kevin Finisterrre claim their goal is to make OS X a better platform -- I hope they are successful.