W00t! I've made a lot of progress with the module lately, and tonight I crossed a highly anticipated milestone. The first icon has now been displayed using theme('icon'). This miniscule function fetches the specified icon, from the right icon set - from the cache..! - based on which icon sets the user would like to use with the theme in question.
Et voilá! An overly huge, misplaced red warning icon making the "Check the status report" message seem like a nuclear disaster about to happen if you don't.
Tomorrow I'll write more about what I've done and where I'm at - for the first time on a tuesday (as is required by GSoC). Somehow, I've been writing the status reports on thursdays. I have no idea why.. :D