I don't know that switching to full repo's solves the problem - you'll still end up with lots of forks, and keeping track of which is the latest and greatest is still going to be a problem. I think the issue is that in a lot of cases these scripts arose out of having an itch to scratch, they're not created as long-haul projects. So, once you've scratched your itch, you're not really interested in the maintenance. I know that was my case with gistcheck.
I think that the real solution is finding someone who wants to manage the maintenance of these scripts. Once you have that, then your problem is largely solved - regardless of whether the scripts live in a gist or a full repo. With an active custodian, there could simply be a sticky thread in the forum with a link to the "official" version (which is maintained) and some bootstrap code to help you pull that down.
That being said, it is confusing with all the variants out there, and it would be awesome if some one wanted to step up and maintain these resources.
Just my $.02.