Uploaded to the Inform extensions site a small extension that adds some tutorial advice to any game: specifically, it introduces LOOK, EXAMINE, TAKE, DROP, INVENTORY, and compass directions, as well as the meta-commands, in an order that depends on the opening layout of the game.
The tutorial mode can be turned off (of course), and its specific advice may be replaced with alternative instructional rules.
Emily Short's Interactive Storytelling 
Interesting; it seems useful.
I am just in the middle of coding some tutorial advice for my own WIP. It’s a bit more specific (I’m using a table of commands that the player might want to try out and suggest some of them every turn as long as the tutorial lasts), but that also means it costs non-trivial time to code. This extension seems like a good alternative for games where you don’t want to go through the hassle of coding a specific tutorial into the game.
Excellent. I know this is related to the casual players trying it out for the first time and wanting a brief explanation of play mechanics. Can’t hurt.
Fantastic addition, Emily. Your creativity and practicality never cease to amaze me.