As I reported yesterday, Microsoft adCenter is adding negative keywords to a campaign level. But a few questions remain. Barry reported on Search Engine Land that adCenter is upgrading more subscribers to the content network on June 28.

Advertisers who are selected will be automatically included and be billed for clicks on ads within Microsoft's contextual program.

According to Barry, you have to opt out yourself if you don't want to be involved in the content network. You can do so by filling out this form.

Discussion at Search Engine Watch Forums.