Don’t care what what a man who publishes gossip blogs predicts will happen to the ad market? Fair enough.Here are some actual data from the front lines: Online advertising sales results from Jupiter Media (JUPM), an odd collection of Web sites, trade shows and (until last month), stock photography businesses.

To spell that out–Jupiter is reporting that revenue per online advertiser dropped 29.6 percent in the last quarter, which ended Sept. 30. And recall that the financial meltdown didn’t really hit until the last two weeks of September.

The net effect: Jupiter’s online media business declined 4.6 percent in that quarter. What do you think the current quarter will look like?

If you want to argue that Jupiter’s an outlier, and that big Web players like Google (GOOG) and Yahoo (YHOO) are still going to be fine, you’re not alone. Yesterday, for instance, someone at Condé Nast’s Web publishing unit told me the company’s still forecasting high single-digit to low double-digit revenue increases for 2009.

But recall that Time Warner’s AOL (TWX) just recorded a six percent ad revenue drop during its third quarter. At some point Nick Denton is going to look less paranoid and more prescient.