google ad exchange

http://www.smh.com.au/business/google-ad-exchange-to-turn-the-game-on-its-head-20101202-18i5k.html

Excuse my ignorance, but how's what google is planning any different to what Adslot does?

I have been a bit tentative investing much into this because I have been worried about how quickly things might change if Google decided to get into the real-time ad auction market.

I would like the opinions from a few 'tech-heads' if possible.