I may be missing the point here, but I don't think that this announcement actually says much about what we as individual publishers can expect as rev share.
What I understand from the article is that 68% of the aggregated revenue generated by all the publishers is payed back by Google to the publishers, probably not evenly.
If the figures given are simple averages (TOTAL_AD_REVENUE / TOTAL_NUMBER_OF_PUBLISHERS) then it is not an useful figure for individual publishers. For example, it may mean that a handful of huge publishers are getting a revenue share of 90% but the vast majority of medium and small publishers are getting 20%. You would still not know how much is the typical publisher getting.
Until I see more information about how the 68% and the 51% figures were calculated and about whether all publishers get the same or similar rates, then I will still have no idea what the effective rev share for a typical small publisher (less than 1,000,000 pageviews/month) is.
The Adsense team have clarified this point themselves in a comment to the original article:
"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." [http://adsense.blogspot.com/2010/05/adsense-revenue-share.ht...]
What I understand from the article is that 68% of the aggregated revenue generated by all the publishers is payed back by Google to the publishers, probably not evenly.
If the figures given are simple averages (TOTAL_AD_REVENUE / TOTAL_NUMBER_OF_PUBLISHERS) then it is not an useful figure for individual publishers. For example, it may mean that a handful of huge publishers are getting a revenue share of 90% but the vast majority of medium and small publishers are getting 20%. You would still not know how much is the typical publisher getting.
Until I see more information about how the 68% and the 51% figures were calculated and about whether all publishers get the same or similar rates, then I will still have no idea what the effective rev share for a typical small publisher (less than 1,000,000 pageviews/month) is.