After loading up the new snapshot, I noticed that a bunch of the entity ids have been changed.

Here are some examples:

• ArmorStand -> minecraft:armor_stand
• PrimedTnt -> minecraft:tnt
• FallingSand -> minecraft:falling_block

(The "minecraft:" is optional)

This is just a heads up for people who will be updating maps and command block creations to 1.11: you will have to change all /summon commands and selectors from things like

/summon ArmorStand ~ ~ ~

to

/summon minecraft:armor_stand

And

/testfor @e[type=ArmorStand,r=5]

to

/testfor @e[type=minecraft:armor_stand,r=5]