From Discovery News:

Cat owners who think their cats control them now have some scientific confirmation: Animal vocalization experts have just identified a special manipulative purr that felines have evolved, in part, to get what they want from people.

The newly identified vocalization, called "solicitation purring," has never been acknowledged or studied before, although cat fanciers, such as the study's lead author Karen McComb, are quite familiar with it.

"In the case of my cat, if he sees you stirring from sleep at all in the early morning he will immediately switch into giving this solicitation purring and position himself next to your head so you get the full impact," McComb, a reader in Behavioral Ecology at the University of Sussex, told Discovery News.

She added, "Asking around, I find I'm not the only one who, if I wake up early, often lie pretending to still be asleep so my cat doesn't start this!"

McComb, who has analyzed communication and cognition of elephants, lions and many other mammals, decided to investigate what could be behind her cat's early morning purring.

The rest of the story can be found here