There should be a website with information about main developers/maintainers:
Product (DRM Intel, DRM Radeon, Mesa) | Component[s] (Maintainer, Core developer, Intel, R200, R300, R600, nouveau, ...) | Real Name | eMail | Name on IRC | Usual time to ask (e.g. 17 to 20 UTC) | Available on IRC channels (#dri-devel, #nouveau, ...) | Working for [Red Hat, SUSE, Linux Foundation, Ubuntu, ...]
I think it would be hard to keep that info up to date.
If you're wondering who's most recently been working on a particular driver, the best thing to do is check the git history.