As you can tell from reading my sig, I have one of the original copies of Ptolus and thought it was a fantastic book. I was a very big of all the Malhavoc releases. Things like Beyond Countless Doorways (Planescape reunion book) and Arcana Unearthed/Evolved were both great. If you look at later developments in 3.5 you see things lifted from his work at Malhavoc. Arcana Unearthed/Evolved introduced racial levels, which were added during 3.5 and some of the 4E Paragon Paths like Beastblooded Minotaur are certainly a "more Minotaur than your average Minotaur" kind of deal.
AU/AE had an increased emphasis on the implement people were using and they mattered. A Magister was nothing w/o his staff, Swordmages cast their spells thru their bladed weapons, etc. What did WotC do with 4th Ed? Weapons and implements really matter. AU also increased casting flexibility greatly from it's d20 origins, which isn't something that was really kept in 4E, but classes certainly stand out from each other and do a good job of covering all the various tropes. AU stood out b/c it had Humans, but nothing else that was familiar. New races, new classes. Taking big chances. That spirit was certainly in 4E.
As far as nothing publicly replacing his work w/dungeonaday.com, hasn't he had a couple of different non-fiction novels he's spent the last few years working on, besides his work w/Paizo regarding Pathfinder? He's had various irons in the fire. I'm curious what his relationship and involvement w/Paizo is at this point if he's officially working for WotC again.
Monte, big gratis on being back at WotC and I hope this means only good things for you. I also hope this means that next year's D&D setting is Arcana Evolved

I think it could translate very well in many ways.
PS If there is a new edition you are working on, remember that feats and talents need to become separate design space.
