While PlayerUnknown's Battlegrounds is still technically in early access, regular patches are still being released to improve and expand gameplay. The most recent patch adds a new weapon/town and fog. This might not seem like much, but every little update means just a few more things to play around with, and that could be the difference between life and death.
The weapon that's been added into PUBG is the Mini-14. It's a 5.56 semi-automatic rifle that's meant to be used for sniping. You can use any optic sights for the gun, and all the sniper rifle attachments in the game will work with the Mini-14 (for both muzzle and magazine). Some other weapons are being updated with this patch too, in particular the Tommy Gun and Crossbow. The Crossbow will now reload 35% quicker, and the Tommy Gun will only be available as a world spawn weapon.
PUBG's new town is called Kameshki, and it exists along the coast of the game's map. If you go into the town of Stalber and head east, you'll be able to find it. While you're in Stalber, you might as well take the time to look around a bit, as some buildings have been added there too. This may be the only map thus far, but it's clear that lots is and will be packed into it.
Last but certainly not least, PUBG is getting foggy weather. On the test servers it will appear fairly frequently for testing purposes, of course. In the main game, fog will be a low probability occurrence, as far as weather patterns go.
Vaulting is still in the works. Hopefully there will be a test for it this November, but there's no final date for its release yet.