I have one of the new SmallHD 702 monitors, and a 13" Retina MacBook Pro.
Connecting the two via HDMI causes no result. No picture on the SmallHD 702, no temporary screen-blanking on the Mac as is typical when they detect a new display. It's like I've plugged a bare cable into the Mac – nothing happens. The System Preferences>Displays pane shows no evidence of an attached monitor.
I've tested with three known good cables, via both the built-in HDMI and a Thunderbolt-HDMI adapter, same result: nothing.
I've plugged a Nikon DSLR and an Apple TV into the SmallHD 702, and both produce a picture.
I've plugged the MacBook (direct and via adapter) into an LG HDTV, and it produces picture (extended desktop, etc.). System Prefs then shows the newly attached TV as expected.
It's only the combination of MacBook and SmallHD 702 that produces unexpected results (i.e. nothing!).