According to a recent AdSense blog announcement and the very email I found in my inbox yesterday, Google has now enabled third-party ads on their content network. Here’s an excerpt from the email announcing this:
Google content network now accepts display ads served from qualified third-party vendors. During this initial release, only ads in English are eligible, although we look forward to offering more options in the future.
By accepting third-party ads, we can attract a greater variety of advertising on the Google content network, which we believe will result over time in increased revenue for publishers and more relevant advertising for end users.
If you’re currently opted in to image ads, you’re already able to receive third-party ads. If not, you can enable image ads to start receiving third-party ads immediately.
You’ll continue to have full control over which ads appear on your site with tools like competitive ad filtering and the Ad Review Center. Also, only advertisers with whom we have proven relationships and who’ve clearly demonstrated commitments to our quality standards may participate in this program. Our policies governing ad content and formatting remain unchanged.