Yes. Google have two types of ads. One is Pay per Click (CPC) and the other one is Pay per Impression (CPM). It depends on how advertiser wants to advertise their website.
Its mainly a CPC ad system and so if you want CPM then you should try other sites e.g. adbrite, clicksor etc.
I think CPM is only available for Premier Publishers. To become one, your site needs to get lot of traffic.