Google has kept its AdSense revenue share numbers a secret for quite some time, but has now decided to disclose them - or at least some of them. They've revealed the percentages for AdSense for Content and AdSense for Search, but are remaining mum on some of the other offerings. Still, content and search are the two biggies.

Is Google's revenue split better or worse than you expected? Let us know.

The company says this is an effort to increase transparency (though the situation in Italy likely played a significant role), and is now displaying the revenue shares right in the new AdSense interface, in the 'Account Information' section of the 'Account Settings' page (the numbers will also be available soon in the existing interface).

"AdSense for content publishers, who make up the vast majority of our AdSense publishers, earn a 68% revenue share worldwide," says Neal Mohan VP, Product Management. "This means we pay 68% of the revenue that we collect from advertisers for AdSense for content ads that appear on your sites. The remaining portion that we keep reflects Google's costs for our continued investment in AdSense — including the development of new technologies, products and features that help maximize the earnings you generate from these ads. It also reflects the costs we incur in building products and features that enable our AdWords advertisers to serve ads on our AdSense partner sites. Since launching AdSense for content in 2003, this revenue share has never changed."

"We pay our AdSense for search partners a 51% revenue share, worldwide, for the search ads that appear through their implementations," adds Mohan. "As with AdSense for content, the proportion of revenue that we keep reflects our costs, including the significant expense, research and development involved in building and enhancing our core search and AdWords technologies. The AdSense for search revenue share has remained the same since 2005, when we increased it."

John Battelle brought up some confusion around a 15% "serving" fee, known as an "AFC Deduction", which he says was commonly used for negotiated contracts with large publishers, but Google says it was never used for publishers who signed up directly on the Google website. The company told him, "There is no 15% serving, or any other, fee for those online publishers."

In fact, Arlene from Google's Inside AdSense team stepped into the comments on the announcement to address this and other questions that had been coming up. She said:

The 68% revenue share for AdSense for content applies to all online publishers, and is not an average revenue share. If you're showing AdSense for content ads on your pages, you're receiving 68% of the amount advertisers pay for those ads. While the revenue share can vary for some major online publishers with whom we negotiate individual contracts, these amounts are not in any way averaged together. Also, there isn’t anything additional taken off the top. You get 68 percent, period.

The transparency around revenue share could become more critical if Facebook ends up offering its own AdSense-like product around the Open Graph. This has been widely speculated upon, and if it ever comes to fruition, it could become a real competitor to AdSense due to the comprehensive targeting abilities that would come with it.

Do you think a Facebook ad network would make for a worthy competitor to AdSense? Comment here.

Danny Sullivan suggests that Google's transparency could lead to competitors offering up better deals, but Google appears comfortable with its competition thus far. "We believe our revenue share is very competitive, and the vast number of advertisers who compete to appear on AdSense sites helps to ensure that you’re earning the most from every ad impression," says Mohan.

At this point, Google is still not disclosing its revenue shares for AdSense for mobile applications, feeds, or games. The reason for this the company gives, is that these are still evolving, and they're still learning about the costs associated with supporting them. Revenue shares may change in the future, but they don't have any changes planned yet.

Does knowing the AdSense revenue share percentages change the way you feel about the AdSense program? Tell us what you think.