The JeeNode Zero takes a different approach from most other boards: components are placed on what is considered the bottom of the PCB, with the top free for extensive silk screen labels.
Here is the bottom side of the JeeNode Zero rev4:
And here is the top, with as much information squeezed in as possible:
(both of these images were rendered by the excellent open-source pcb-stackup utility)
As you can see, most of the information needed to use this board in a project is clearly labeled and documented on the PCB, so you won’t have to search for additional docs in many cases.
The top of the board is also where a new side-sliding coin cell holder can be mounted, as well as well as the location for the new “µPlug” connector pads.
The LED is a special one, mounted on the bottom but pointing sideways, with a small cutout in the PCB to try and make the LED visible from the top as well.
Also new in this revision is provision for an optional “UFL” miniature antenna connector, to allow using something other than a 𝛌/4 wire antenna with the JNZ. Note that these connectors are usually rated for only up to five insertions before they break or lose their springiness.
There was not enough room left on this board for mounting holes, but as a compromise, small quarter-hole circular cutouts have been added to the FTDI side of the board, so that you can at least lock the board in place with a few stand-offs and M3 screws+nuts. The other way to fasten this board, is to mount it upside down and treat it as a large through-hole component.