This is sad news. After reading the news yesterday, I decided to watch the ending to The Muppet Movie, as well as his Road Runner short Little Go Beep.
I enjoyed all the insight he gave about the making of the ending of The Muppet Movie, as well as his memories of visiting the Sesame Street set often in the early 1970s. When I first learned of his "My Name is Earl Kress" blog on the Golden Age Cartoons forum, I mentioned the news somewhere on this thread. I started a page for Earl Kress at Muppet Wiki, though it was later taken down for not being relavent enough (the talk page can still be viewed).
I think I was the first to ask anything close to who he was, before we learned his name, and he mentioned he wasn't trying to hide his identity but wasn't ready to reveal himself yet. And when a Tom and Jerry DVD came out I looked at the back packaging and saw "Earl Kress" listed as doing commentary, and figured out that was him (before he revealed his name to us). Similarly, he was a member of the Golden Age Cartoons forum under the name Daws Butler Jr, but I thought that was really Butler's son. One time on the forum he mentioned a fact about the Top Cat DVD, which he'd mentioned on his blog, and I asked about it, confused (another member told me via private message that he was Earl Kress).
I've often desired to have my own cartoony live-action series, and I had it in my mind that if I achieved that goal, I'd want at least one person on the writing staff who was more experienced with writing for animation, with Earl Kress being at the top of the list (while I know many of the shows he wrote for, I don't know what episodes he had written).
I wonder if The Muppet Mindset or Tough Pigs will point this out.