KitKat dialer could show ads
With the new KitKat dialer, the contacts list will be prioritized based on the people you speak to the most. You will be able to search for phone numbers from local businesses. Caller ID will search for incoming numbers not in your contacts list with a list of business numbers, and will also call up a Google Maps listing if the call does originate from a business. The new dialer features a card based UI similar to what you see with Google Now.
source: +RonAmadeo, AndroidPolice via AndroidAuthority
UPDATE: Ron Amadeo has updated his Google+ page and has spread the word that the code found on the KitKat dialer's APK is old code and the good news is that Google is not-repeat NOT-planning on putting ads on the dialer. Perhaps this was a trial balloon, who knows? But regardless, no one on the consumer end liked the idea, it is not happening, and we can all now breathe a little better.