Google has some numbers on there sites but like many other things google it depends on who you are and what your site is about. Google has various levels of publishers but premium seperates itself because google will guarentee a level of revenue. The contract guarentee is generally much lower then what the website would make but it is a nice saftey net for publishers who feel like there income is volitale to get guarenteed revenue. Also the revenue share is slightly better for premium publishers but I forget what the margin is off the top of my head.
Hey, i know on google is says 20m page views per month...do you know how much income you would be looking at before you are considered? thousands/m, ten thousands/m etc...