On the subject, how about a bit more transparency about pending updates and update policies? For example, GOG's offering of AI War is more than 2 years out of date. AI War's developer says they sent a new update to GOG, but it clearly never arrived. The GOG store page for AI War makes no mention of how badly outdated GOG's offering is. The only ways to discover this are for the in-game updater to successfully call home and then start asking to update (and, according to another recent post, that update doesn't even install correctly, though it runs fine once the user works around the bad update) or for the user to go browse the developer's changelog and notice the severe discrepancy between the in-game version number and the entries in the changelog.

As for specific transparency, several things come to mind:
1) For games that GOG has no intention of updating, tell us that it is abandoned. Where possible, indicate whether it's because the developer has abandoned it upstream or (as with AI War) GOG elected to abandon it despite ongoing work from the developer.
2) For games that still receive updates, provide visibility into the existence of not-yet-released patches. Destro says that a developer uploaded a patch that then got orphaned in an internal queue. None of the customers can see that. The developer may have thought that he was waiting on GOG, and GOG apparently was waiting on the developer to make further decisions. If users could see that the patch was in the pipeline, they could remind the appropriate party that more work was needed.
3) For games that receive updates, some system (not based on GOG Galaxy!) to detect that they have been updated would be appreciated. I don't think GOG really wants people speculatively redownloading installers to check the version, but that's the only method I know to use at the moment. (I know I can cancel the download when the browser prompts me to pick a filename. I'd rather see a listing of all my games and their real versions.)