The Mayo Clinic is recognizing the health benefits of weight lifting:
You know exercise is good for you. Ideally, you're looking for ways to incorporate physical activity into your daily routine. If your aerobic workouts aren't balanced by a proper dose of strength training, though, you're missing out on a key component of overall health and fitness. Despite its reputation as a "guy" or "jock" thing, strength training is important for everyone. With a regular strength training program, you can reduce your body fat, increase your lean muscle mass and burn calories more efficiently.
MayoClinic.com: Strength training: Get stronger, leaner, healthier