[joss82]

Communication.

Communication! Communication! Communication!

If any part of your product requires people to communicate with each other, then the team members lying on vastly different time zones will have low efficiency because information round trip time will be larger than those of the local (or time zone near) ones.

[ako]

Yes, Specifically being able to communicate in front of a whiteboard is crucial. Exploring ideas, creating a shared understanding, etc, all becomes a lot easier if you can support this with some interactive visualization on a whiteboard. I feel disabled if I have to communicate without a whiteboard.