Google allows up to three ads on a page.
Don't know if its been posted here yet, but...
Quote:
Multiple ad units
To provide even more value to your users, and to help you further monetise your web pages, we are allowing publishers to place up to three ad units on every web page. Our system will automatically recognise the additional ad units, and will serve unique ads to each. Your ad units can each have different colour palettes, formats, and alternate ad URLs, providing you with the flexibility you need to incorporate Google ads into your site design. Please read the Multiple Ad Units section of our FAQ for the full details.
https://www.google.com/adsense/new
Good news I think. Will be useful for those who have ads mixed in with their main content.
Views?