http://store.steampowered.com/app/314160/
And it's out!
Was on for 80% off earlier today, which made it $5 - and probably means that it'll be back on for that price sometime again in the next two weeks. Keep an eye on it!
The reported additions are Win 8.1 support, built-in multiplayer, CPU optimizations/stability fixes, and a bunch of new aircraft and objects. It seems that most add-ons are unaffected and FSUIPC works properly. Promising so far!