Todo

Planned (and current) Glk spec updates:

First update (spec 0.7.1)

Released Jan 22, 2011. (These are simple updates which don't require a whole lot of design work. See Glk 071 draft spec changes.)

glk.h header should use 32-bit typedefs for glui32 and glsi32. (Include stdint.h.)
A way to set line-input terminator keys (so the game can react to function keys, etc, during line input)
A way to set whether line input is automatically echoed to the window, when input is completed or cancelled. (Currently it always is, but in certain cases you want to suppress that.)
The always-popular "draw a border between these windows" flag.
Calls to decompose and renormalize a bufferful of Unicode text.

Released Feb 17, 2011. See Glk 072 draft spec changes.

System-clock API (get the current time, in Unix timestamp form or a broken-out date/time structure)

Released Oct 10, 2011. Improvements to the sound-channel API. See Glk 073 draft spec changes.

You can pause and unpause sound channels
You can tell a sound channel to change volume gradually
You can start several sounds at exactly the same time
A single gestalt selector covers all sound functions now, so you don't have to write complicated feature tests

Released Jan 29, 2012. See Glk 074 draft spec changes.

Recommendation for unifying the way interpreters handle file suffixes. For data files, at least.
A way to embed data files in a Blorb archive, so that the game can read them directly.

A way for a game to customize its presentation: fonts, colors, margins, etc. Also includes features for including HTML display directly in games.

Glk Stylesheets: Overview
Glk Stylesheets: All the Details
Glk Stylesheets: The Short Form (for people who don't want to read about CSS or HTML or anything, they just want it to work)

Provide a glk_tick() macro, and document that calling it will be free (a do-nothing macro) if the library doesn't need to do tick work.
Multi-interface changes for glk.h. This would require changing every API call to take a context pointer, with #defines for backwards compatibility to existing code. (Both app code and library code require backwards compatibility! Headache.)
Network API