When David Letterman announced his impending retirement from late night TV, Mike Mills of R.E.M. was the first to tweet the news. Afterward, Mills and former bandmate Peter Buck joined singer/songwriter Joseph Arthur and a string section in a cover of “Walk On the Wild Side,” paying tribute to late legend Lou Reed. In contrast to the smoky, jazzy original, Arthur’s version is more of a dramatic ballad, with a gentle piano melody at the center of it all. And it’s a fine cover — even quite pretty. But as touching a tribute as it might be. The detached cool of the original seems to have been mostly abandoned, which is too bad, but then again, if it sounded exactly like Lou’s version, then there probably wouldn’t have been any point in covering it. All the same, Arthur, Mills and Buck put a fine cap on the careers of two greats with this one, beautifully executed take.