Shuttle
A shuttle service is the same as a multi project wafer.
On 30th June 2020, Tim Ansell announced the collaboration between Google and Skywater to provide a free shuttle service in his FOSSI dialup talk.
These slides taken from his talk show the overview:
Caravel
Normally in an MPW you would have the whole die to yourself. In the Google/Skywater Shuttle all the designs will be within the user project area of the Caravel harness. Caravel has its own RISCV processor and a neat datasheet. The idea here is to make it easier to bring up and debug your designs at the cost of some area.
Read this post to find out what you could fit in the user space.
The Google shuttle will return chips in type of packaging called Wafer Level Chip Scale Packaging.
Requirements
Efabless have put up a page that has more details on the requirements for entry to the shuttle.
Course feedback
I saw that Google was doing the free shuttle service and I thought that would be really cool to get into. I had no idea how to even begin such a process and then I saw the course and it's like “Hey this this is exactly what I need!