Yes, orange juice has a pH of 5 and teeth can be damaged by anything with a pH lower than 6.2. That is not to say you should not drink juice, just chug it down and don't keep it in your mouth too long.
You can also drink it with a straw to minimize the contact with the teeth then give your mouth a quick rinse with water when you're finished to neutralize the acid. At least, that's how I drink juices and soft drinks.
Oh, and I carry gum with me (any kind) to use if I can't rinse with water. It increases saliva and helps to wash away the juice.
Many foods and drinks contain acids/sugars that can damage your teeth and since many of them are healthy for your body in general, they shouldn't be avoided. As long as you're practicing good oral hygene and it should be fine. Another thing to consider is dry mouth. Your saliva somewhat serves to rinse some of the acids during the day, but if you have dry mouth that little extra protection is not there. I think addressing that issue or compensating for it by swishing with water after eating or drinking can help prevent damage to the enamel.