This is not true. If you have bad form, don't stretch properly, or overexert yourself, it can be bad for the joints. However, running in general is good for the joints.
http://www.runnersworld.com/health/b...ng?page=single
I have been a long distance runner since I was 13. I am now almost 31 with no joint issues. In fact, the only times I feel real joint pain is after consecutive days of surfing. It is easier to overexert yourself fighting currents or even riding a wave (push, pull, crouch). I am not a slow runner either. I average 7 minute miles and run about 5 miles a day.