I am looking forward to this being a default feature. Glad to hear it made it in.
I constantly use it on my sites where we (as a team) edit documentation and what not.
Having an inline editor helps us organize the data in front of us, and the ability to scroll up and down and go back to the editor and continue editing.
What I especially like about inline editors, they've got the full width of the post, so it's more accurate as to how it looks.