Sounds like something that should be part of a theme to me.
If you wanted to make such a theme, in-place editing isn't really difficult, you're just swapping visibility between a text block and a text input. Client-side you would only do the swap for the correct user(s), and then server-side verify and actually change the topic title.
Like NodeBB, Ghost is a relative new project, so it definitely stands out. They're also doing much to really turn around the blogging platform industry, which has been stagnant for quite awhile (WordPress really cornered the market there).