FWIW, this is the mail I got:

Folks, we have a new element to the Early Arrival protocol this year:
if you're getting there before Monday at 12:01am, for training or for
setup, please read and understand this message!

Land grabbing, or carving out space for your later arriving friends,
has been against policy for several years now. This year, the Camp
Placement folks are bringing a new detail to the mix: Early Arrival
requires Early Placement.

When you get to Black Rock City, you will NOT be allowed to just set
up camp wherever you wish. EVERYONE who arrives before 12:01am on
Monday will need to contact Placement on the radio to work out where
you will be camping: you will, in effect, be treated as an early-
arriving theme camp, and mapped as such.

You are strongly discouraged from setting up your theme camp
accoutrements when you arrive: you are there early because you are
there to work on infrastructure, not on your personal camp; you're
free to work on your personal camp when every other participant can,
after 12:01am on Monday.

If you go ahead and set up camp without consulting with Placement,
you will very likely be told to move your camp.

They're serious about this, folks... please factor this into your plans!