I missed the first 1/2 hour of tonight's show so unless they did something for Don then, they didn't even mention him at all.
The show itself (final show of the season) was fairly lame (the hour I saw).
Several former castmembers came by for cameo spots including Mya Rudolph, Norm MacDonald, and even Amy Poehler came back to host Weekend Update with Seth. Unfortunately, it was way too short, rather lame, and unfunny except for "Really! with Seth and Amy" and Will Ferrell's Ghost of Harry Carey.
Ferrell's thanks at the end mentioned,among others, Tom Hanks and Ben Affleck. I think it was Hanks (or Affleck) in that final sketch pretending to play the clarinet. And he made a point to thank and hug Darrell Hammond. I got the impression that maybe this was Hammond's final season. He's been there for forever but has shown up for maybe 1 or 2 sketches the last year or two and always well after midnight.