Here is how we currently impose pageview limits DURING THE BETA period.
Most approved websites are limited to 10,000 pageviews per day. However, some websites were approved with an additional 100,000 pageviews per month. To see how this works, let's take for example the month of May. For the past few days since the beginning of May, let's say your traffic was as follows:
May 1: 45000 => 35000 over the 10000 daily limit
May 2: 30000 => 20000 over the 10000 daily limit
May 3: 32000 => 22000 over
May 4: 40000 => 30000 over
May 5: you flat line at 10000
If you add all the daily overage (35000+20000+22000+30000) from May 1-4, you've exceeded your daily 10k and now you've also exceeded your monthly allowed overage. After hitting both these limits, you will flat line at 10000 per day until the next month when your monthly overage starts over.
Hope that helps explain what you're experiencing.