Grand Theft Auto V launched today at around midnight GMT worldwide. This corresponded to 7PM EDT for those of us in North America. Well, add a little time for Steam to unlock the title and a bit longer for Rockstar to get enough servers online. One thing you did not need to wait for was new video card drivers. Both AMD and NVIDIA have day-one drivers that provide support.
You can get the NVIDIA drivers at their landing page
You can get the AMD drivers at their release notes
Personally, I ran the game for about a half hour on Windows 10 (Build 10049) with a GeForce GTX 670. Since these drivers are not for the pre-release operating system, I tried running it on 349.90 to see how it performed before upgrading. Surprisingly, it seems to be okay (apart from a tree that was flickering in and out of existence during a cut-scene). I would definitely update my drivers if they were available and supported, but I'm glad that it seems to be playable even on Windows 10.