The Google AdSense blog announced that they will be adding additional email preferences to the account page. Here is a picture of the new preferences page:
I personally do not see these new preferences under the contact preferences page, but I guess it will show up for me shortly.
In a WebmasterWorld thread, AdsenseAdvisor said:
These new email notification preferences were created in response to feedback from you guys that we haven't been giving you enough opportunities to hear from us. Until now, you've all been limited in the kinds and formats of information you could sign up to receive by email, so we wanted to give you more options and better control over the email offers you get from us.
If you sign up for all the new categories, you'll be eligible for all kinds of great stuff that I probably shouldn't give too many details on yet.
Forum discussion at WebmasterWorld.