Valve has told me that the 1.87 update is now live as a Beta. If there are no issues with it, it will go live as a regular update either this Friday or Monday. So if you don't play betas, you won't have more than about 48 hours to wait to get version 1.87 as a normal update trough Steam.
Important: If you want to play the Beta in coop, you'll need to make sure the people you play with are also running this Beta. You can't mix 1.86 and 1.87. Of course in single player this doesn't matter.
The Steam command line to play the Beta:
First beta of a new gamemode called King Of The Hill (see previous post below for more detail)
New updated Sentry gun. The default gun now does a lot more damage. Sentrygun cooldown is also faster so you don't need to wait too long before they're operational again
Bosses health and kill bonus reworked: Some bosses (Butcher, Axe, Cutoff saw) won't get more armor as the game progresses and remain relatively easy to kill. Minigun and AK-47 bosses will attack more intelligently later on in games. Bonus for killing a minigun or AK47 boss is doubled from 25,000 to 50,000 Xp.
Bonus for killing a Zombie Bomber is doubled from 2500 to 5000 Xp
In on-line coop shared xp mode, other players' perk selection messages stay on-screen longer
Added an option for setting the amount of ground blood splats
Text chat now also possible while pausing the game
Lobby owner now has the ability to kick players from lobby
Ghost powerup frequency increased.
When at 100% health, powerup pull/snare for med kits is reduced
When both weapons are locked, powerup hook won't pull weapons towards you
Super Shorty weapon damage increased by 30%
AA-12 weapon damage increased by 15%
Visible map space at the bottom of the Oil Platform level is now larger
Medkits walked over by players with 100% health can now be picked up by other players
Oil Platform level zombie flows much better
Mouse speed/sensitivity set back to as it was before the 1.86 update
ALT-TABing away from the game resets the Windows cursor rectangle back to the entire desktop
Pressing Enter during text chat/console while the perk screen is up won't accidentally select a perk anymore
Menu options easy to click on regardless of screen resolution