Okay, so, seeing how I never have time to GM something major, and how there's a number of GMs without players and players without GMs on IRC, I've gone and made a shared campaign setting, with PCs all hanging out at a certain place, and getting to run as soon as work is available (say, through the owner). Speaking mechanically, we just have a channel with GMs and players on it, and as soon as someone's ready to run, he has a ready premise, ready runners, and everything. It's initially geared towards short single or couple-session runs, but that's not a requirement.
The channel is #shadowrun over at suptg; here are the campaign notes.
As the nature of the shared setting allows, we're looking both for players and GMs.