Thanks for the insight, Bob.

Surprisingly my shoulder feels much better today -- 48 hours after the injury. Only a little bit of pain when I lift my right arm over my head and touch my left shoulder. But I'm basically pain-free.

Would the pain go away this quickly if it was a "new" AC joint rupture? When I injured the same shoulder 3 years good, it took 3-4 weeks for the pain to go away. To my untrained eye, I only notice the the bump when I extend my arms laterally. Could the bump/step-deformity be from that 3-year-old injury? If so, does this mean my shoulder is more susceptible to injury? I don't mind the minor deformity, but if it means I'm at an increased risk of injury, then surgical repair makes sense. My anecdotal evidence seems to indicate no increased risk -- I've only injured this shoulder twice in my life (I don't play any full contact sports, but basketball and mountain biking do involve some contact).

I do need to improve my posture. At 6'7, I've fallen into the habit of leaning down to talk people. Can you recommend any exercises for improving posture? Balancing a book on my head... haha.