Are there advantages for Protoss gateways over warp gates?

Solution 1:

It has been suggested that the many answers be combined into a single CW answer. This is that answer. Feel free to update with any additional information.

Advantages of Gateways:

• Rally point can be set.
• Queuing of units is allowed. This means you have more time to remember to train units, reducing downtime for some novice players. It also means production of the next unit can begin immediately after the last one has finished.
• Units can be canceled.
• Units can be created using only hotkeys (no mouse clicks).
• Units cannot be attacked until they are spawned and ready to attack (whereas units warping in can be attacked during the warp in period).

Advantages of Warpgates:

• Units can be spawned quickly anywhere you have a pylon.
• Queuing of units is not necessary -- you do not commit resources until moments before the unit is spawned.
• Army composition can be decided at the last minute.
• Cooldown period is incurred after the unit has been produced, which can be an advantage during a battle.
• Cooldown period is shorter for warp gates, allowing you to train more units from warp gates than from gateways in the same amount of time.

Solution 2:

Gateways can be rally-pointed. With warpgates, you must click the exit location every time you create units.