There's the obvious updates from tonight (new guns, new achievements, etc). But here's what you probably missed. Emphasis added for the interesting points.
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Added new attack animations to most melee weapons
Added new speech for the Heavy and Demoman
Teleporter effect no longer shows up on invisible or disguised SpiesSpies disguised as their own team can now capture control points
Increased force taken by pipebombs by bullets and explosions
Fixed exploit where clients could start benchmark mode on servers
Minor fix to stat gathering to prevent players using sv_cheats to easily garner achievements
For mapmakers:
Mapmakers can now directly place the tf_gamerules entity into their map. Fixes Hammer thinking the inputs to it are broken
Mapmakers can now place Engineer buildings directly into a map, with an option for them to be invulnerableGranary
Added setup time logic, and gates to the middle2Fort
Added medium ammo and health to basement hallways
Added small ammo and health to top of spiral==================================
The ammo and health on 2Fort will hopefully cut down a bit on turtling (they'll help out anyone who actually managed to make it down there in the first place)
Setup time on Granary (if it is what I think it is), will hopefully make it less of a steamroll map. Very nice.
The idea of adding engineer buildings in a map is pretty cool, but giving the option of making them invulnerable seems excessive. Perhaps this could be used to create THE ULTIMATE SPY MAP?
<3 the pipe-bomb and spy fixes as well as the benchmark prevention fix (just one day late

), lol at trying the stop the sv_cheats achievement whores.