(Hat Tip: Kaushik from Ortuk)
It looks like after testing Ads on Orkut profiles, Google is slowly experimenting with AdSense within a few Orkut communities.
Here are several screen shots from the APPLE : iPhone now with 3G :) forum...
...the India Pakistan Friendship Club forum...
...the United Nations forum...
...and a personal favorite of mine the Brain Teasers forum.
I came across numerous other forums with Google Adsense being proudly displayed, although a high number of them seemed "broken" which may be more on my end since I am using the latest beta of Firefox 3 (which has yet to support GreaseMonkey and Google Gears).
Google previously included Adsense within Orkut, before mysteriously removing them (which may have been due towards users blocking them with GreaseMonkey hacks).
Although there is no word on whether or not Google will share Adsense revenue with forum owners, they have allowed users creating Orkut Apps to display adds alongside their application pages.
Hopefully Google considers sticking with the ads (or even sharing revenue with users), as they could help not only reduce the cost of running Orkut, but help pay for new features for the site as well.