I guess too many factors are included to determine what percent publishers receive. It depends of content, referrer, visitor habits, time spent on page, ad relevancy and many many others (smart pricing for ex.)... Due to financial crisis, number of competitions is sliding slowly down, so this also reflects to our earnings.
check out Google's quarterly report before jumping to conclusions: http://investor.google.com/releases/2008Q4_google_earnings.html
I'm 100% noob at this, but I think you have to remember that many of the clicks come from people doing searches on Google.com and clicking on the ads there. Of course since this is not an "adsense for search" through a publisher 100% of that money goes to Google. with that in mind I would not be surprised if the payout percent to publishers is closer to 75-80%...but like I said, I am a noob and could be way off on my thinking.
Being a adsense publisher and advertiser ..I can say from my own observations that adsense pays us between 60% to 75%. 33% is just wrong.
I think it also depends on the click through rate to define each click cost. i'm running a financing site, which has the highest keyword cost up to $40, but sometimes i even received $0.20 for one click.
I'm not taking either side, but I'm pretty sure that 95 percent of googles revenue is from advertising.