very very nice informations thank you very much mr suma

They can monitor how often an ad is viewed, as long as the ads are interactive ones ("utilizing the set-top-box"), ie, ones that require the viewer to press this or that button to view and stop viewing, or to choose options.

These will be sort of "press the red button" type of ads you get in digital tv; not the usual ads that roll in the ad slots, which is linear.

Back in January of LAST YEAR Robert Cringely wrote about how Google would be doing this – and how they plan to go even further:

http://www.pbs.org/cringely/pulpit/2006/pulpit_20060105_000878.html

"A Commercial Runs Through It: Google's Grand Plan to Take Over TV Advertising"

"Google will cut a deal with every network to customize their ad spots for every viewer. For a small cut of their ad revenues, Google will handle all customization costs, hardware and software. The networks will all go along because the customized ads will be so much more profitable that it would make no sense for any network to refuse."

Hopefully those set top boxes are powerful enough to run Adblock Plus. Luckily I don't watch TV, so actually I don't care :)

BTW, you can sign up here:
http://services.google.com/ads_inquiry/tvadsbeta