Thanks for posting this SirDave
But The game doesn't seem to be listed as a Special Edition. The only reference is at the bottom of the Features list with this..."SE edition features several new puzzles". I don't see any mention of a new area or that "Knut is hoping that this will bring in some new income to support the completion of Rhem 5". You say "Apparently" he needs funds for Rhem 5, is this just your opinion or has he stated this?
Direct quote from the email:
"The (Steam-)Rhem IV would include a new area and some new puzzles. But what's even more important, this would help to support the further work on Rhem 5."
I can't be sure that the official name will be Rhem 4 SE, but as you saw, the SE moniker was used in that link. Maybe it will be called a Director's Cut.
Of course, it will have to be called something to distinguish itself from the original. Maybe Knut hasn't gotten that far yet.
It does occur to me that I don't think the Rhem games have ever been on Steam (I could be wrong) so maybe it will just be The Steam Rhem 4...