Woah lots of spy buffs, I really hope it doesn't make them over-popular:
Looks like a few new counters to fire, Jarate, Pyro Air Blast etc.
Spies disguised as enemy spies now get a random mask to help complete the disguise, and their target id will be set appropriately
Spies disguised as medics now have an Ubercharge: line in their disguise target info
Spies that disguise as a player using an unlockable now show that unlockable in hand
Spies can now use enemy teleporters
Looks like a few new counters to fire, Jarate, Pyro Air Blast etc.