After Google began testing new AdSense fonts back in May of this year, including testing comic sans - Google has finally decided to drop it based on publisher complaints.
AdSenseAdvisor at WebmasterWorld said:
Based on publisher feedback, we have removed Comic Sans from the current ad format experiment. Thanks again for your continued feedback and suggestions. We welcome any further feedback that you might have and assure you that it'll be passed onto the relevant team.
I am not sure if they should have removed it completely. It would have been nice to have it as an option and give publishers the ability to pick and choose which font types they would like to opt in on. Why are you able to pick your sizes, backgrounds, corner styles but not your font type?
In any event, Google removed Comic Sans completely from the font selection for AdSense.
Forum discussion at WebmasterWorld.