Since he's retired from the Late Show and handed off to Stephen Colbert, David Letterman hasn't had much time or reason to be in public - and, very likely, only does it when it actually means something to him.
Therefore, it obviously meant a lot to him that Pearl Jam - a band he had on his show many, many times - were being inducted into the Rock and Roll Hall Of Fame and why he decided to turn up for the event.
In an impassioned fifteen-minute speech about the importance of live music, Pearl Jam's career and his own, Letterman laughed and joked with the audience like it was the old days - except Letterman's got a beard that'd make him look like the fourth member of ZZ Top.
Take a look.
Via YouTube