Via [url=http://blog.counter-strike.net/index.php/2015/12/13409/]the CS:GO blog[/url]:

[quote=Valve][MISC]
– Client bone setup performance optimizations.
– Fixed bullet hits on players beyond max bullet penetration distance always counting as penetration hits.
[KILLER REPLAY]
– Fixed sometimes incorrect in-scope fog and blur in Killer Replay.
– Fixed some instances where a player could get stuck in Killer Replay.
[GAME STATE INTEGRATION]
– Bomb plant timer Game State Integration event is now slightly delayed when playing on Terrorist or Counter-Terrorist team.
– CDN URLs for images of weapons and weapon finishes are now available in items_game_cdn.txt
[STEAM CONTROLLER]
– Added support for haptic feedback.
– Use steam_controller_haptics convar to turn haptics on or off.[/quote]

Rumor has it:

- Here's stuff that changed (some stuff from a Dota 2 main client update released just seconds earlier is also mixed in): [url]https://github.com/SteamDatabase/GameTracking/commit/f6eb67e0275f3f390ae0ceecf25d5bea1e429dd5[/url]

- Size is ~20 MB

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[B][I]Final Warning![/I][/B] If you are on a Mac and you're still using Mac OS X Snow Leopard (10.6), be advised that Steam client support was killed off for Snow Leopard effective November 10th. Mac OS X Lion (10.7) or newer is now required to acquire future Steam client updates, but if you're stuck on Snow Leopard for whatever reason, you should be fine for a while and you should still be able to play CS:GO still, just that you won't get updates for your Steam client. However, a future CS:GO update could move the minimum Steam client version up to one past this date. If possible, make arrangements to move to at least Lion or Mountain Lion, preferably Mavericks or El Capitan, otherwise, you may be left behind if and possibly when a future CS:GO update moves the minimum version up past the November 10th update.

This is the last warning.