There wasn't much information in this DC Source post about Action Comics #900 but it still made me happy. Here is the link and the limited info:
Superman versus (I’ll argue) his greatest villain. How much more apropos can you get for a landmark cover to Action Comics?
But wait - there’s more! In addition to a 50-page lead story by the team that’s been punching this book out of the park for for the last ten issues, Paul Cornell and Pete Woods, the oversized 900th issue will also feature short stories by some very exciting names to be announced soon.
So the David Finch cover is pretty slick. The image of Superman getting out of his civilians somehow works for his return to his title. Sort of like 'okay ... I'm here and ready to work' vibe.
I wonder if this is going to be like Superman/Batman #75 with a number of 2 page stories by high-powered creators celebrating Superman's return.
Lastly, I was glad to recently learn that Paul Cornell is sticking on after this Lex arc and will be writing Superman. I have enjoyed this Luthor run enough to want to see what he does with the Man of Steel.