[Update]: These are now shipping, and will start at $1,200 for the monitor (while B&H says pre-order, the SmallHD site says shipping in 7-10 days). It will be $1,500 with the new Sidefinder clip-on viewfinder attachment.
While it's nice to have giant monitors for when you've got a decent crew or your camera is built up, there are plenty of times that you just wish you could use your phone as a reliable monitor for a small camera or as a director's monitor (with certain tools this is possible, but it's not always an ideal solution).
SmallHD essentially introduced just that today with their new 502 external monitor, that features a 5" 1080p screen with HD-SDI and HDMI input/output/cross-convert, and it's powered by Canon batteries. You can check out the intro video here:In terms of color accuracy, SmallHD claims that it is 85% NTSC Color Gamut, which puts it right in between the DP7-Pro LCD and OLED displays (which are 50% and 100%, respectively). The weight is going to make this perfect for smaller cameras and setups that already have a monitor or two attached. As I said above, I think this could be really terrific as a super light director's monitor, once you add in the wireless solution and a handle.
With smartphone screens getting sharper and bigger, it's only a matter of time before we see more external monitors like these. Typically what happens is the smartphone makers will be the only ones who can use them for a year or two (sometimes longer), and then they start selling them to third parties.
SmallHD doesn't have a price or availability yet, but we should find out those details relatively soon, and we'll be sure to take a look at NAB. You can read more about the monitor here.