We need to make sure we can package the IC after the wafer has been diced into individual dies.
A common way of packaging ICs is to connect them to a leadframe by bonding tiny wires between the leads of the leadframe and the pads on the die.
The big bond pads around the outside of the IC often include ESD protection diodes, Input/Output drivers and so on.
This picture shows raven, an IC from Efabless. You can see around the edge there are the big bond pads and the power and ground lines. This structure is called a padring.
The padring used in the Google shuttle is included in Caravel.
I found that during the week that I was getting prepared for MPW4 was probably the happiest I've been in a long time. I like the challenge and difficulty of it, but it's still done in an approachable way that was not completely over my head.