Looks like big changes are on the horizon today for domain parking.

In the past, you had to sign up with a parking company to park your domain. The parking company would use feeds from Google or Yahoo! to serve ads.

Now you can bypass the parking companies altogether and go directly to Google:
Inside AdSense: Extending AdSense for domains to all publishers

Theoretically, this should result in more parking profits, as you are cutting out a middleman.

I would expect Yahoo! to follow suit in the near future!

I would also worry that at the beginning Google pays well to put the parking companies out of business. Later on, once the parking companies are gone, Google cuts payout dramatically.

While the news are looking great at the moment, I too fear your above point. This is the standard technique that corporates use these days. As profit margins are squeezing up, the are removing middle men and reaching directly to their customers.

Google Adsense for Domains is now available to Indian publishers. You can read more here. Has anyone tried it out?

I put a bunch of domains on Google for Domains in the last few days. So far, the number of hits is small (more hits than on Sedo, but still small numbers). It's too early to tell. I dipped my toes into the pool with one three-letter .in domain. In this case, the advertisements they put on the domain were totally irrelevant to the Indian market. I pulled the domain off Google, put it back on Sedo, then pulled it off Sedo and put it back on Google, hoping that my first attempt was an anamoly and the second attempt would produce better results. Sorry, it didn't work out that way. On my second attempt I got exactly the same wrong advertisements as on my first attempt. In other words, in my single example, Google for Domains for my .in site was wrong, wrong, wrong.

Second post about a half hour after the previous post: I just checked into the results for the domains I parked at Google for Domains. All of a sudden the numbers are much higher. Many of the domains I parked today have gotten hits (no money, but visitors). This result is encouraging. On the other hand, I entered a Japanese language domain on the list. Within minutes there was a Japanese language page with lots of links. But none of the links had anything at all to do with the single-word domain name (the word for 'tattoo artist'). From this limited experience I draw the conclusion that Google for Domains is not yet ready for non-US domains.

does it work for developed/published sites or also on parked domains..(cant log on to my account)

I'm neither an expert nor a salesman for Google, so my answer to your question is not definitive. My guess is Google for Domains is NOT appropriate for developed/published sites or for domains parked at other parking companies. It appears to me to be a service for otherwise unconnected domains. It parks sites that aren't developed or that aren't parked anywhere else. In order to sign up a site to Google for Domains you have to go through some annoying steps (that become automatic after two or three times) that make it impossible to do anything but display the site on Google for Domains.