Funny, I had this Cat tip of the day for today:

"In Or Out?
Cats adapt quickly to circumstances, whether they're indoors or out. There's no question that the outdoor cat is at far greater risk than the housecat. Outside, a cat can fall victim to dogs, cars, wildlife and other hazards. Fights with other cats are a fact of life for the outside cat, and the chances of both pregnancy and infectious diseases are much higher.

To put things in perspective, think of it this way--the average indoor cat lives upwards of 15 years. The outdoor cat has a life expectancy of 4 to 5 years."