Pixtronix is a 6 year old startup that has been quietly working on MEMS based screens (similar to Mirasol). But while the tech is similar, there are a number of key differences. The Mirasol screen is a low power reflective display. Since it cannot have a backlight, the demo and the production unit all have front lights. The Pixtronix screen, on the other hand, is backlit, and it uses a little more power than Mirasol but still only about 25% the power of a normal LCD.
One reason you may have never heard of Pixtronix is that when they are at shows they are generally in the booth of one of their business partners. Up until the sale, they had ongoing deals with 3: Samsung, Hitachi Displays, and Chimei Innolux. You might have seen their screen on display at SID Display Week 2011; they were in the Samsung booth. (The several photos in this post are from SID Display week, actually.)
Yes, Samsung, a company that owns the screen tech company LiquaVista, was also working with Pixtronix.
I'm still waiting to hear back from Pixtronix, so I do not know just yet whether the one tech will supplant the other, or if they might be developed independently, or if the companies might merge and combine their efforts. But I do know that Pixtronix is still quite a ways away from having a screen on the market. The last I had heard was that Samsung planned to have a Pixtronix based device in production in 2013.
But it is important to note that Pixtronix was working on several screen sizes (from 2.5" to 10"), not just the single size that Mirasol has released. Check out the video at the end of this post. It was shot at SID Display Week 2011 and shows off a number of Pixtronix screens including the 10" model (about 3:30).
Mirasol, on the other hand, is already on one gadget, the Kyobo eReader. This device has a 5.7" screen and is marketed as an ereader by Kyobo, a South Korean bookstore chain.
I don't know about their production plans, but I was told in the past that Pixtronix had partnered with Samsung, Hitachi Displays, and Chimei Innolux because they would also be Pixtronix's production partners. Pixtronix's screens can be produced on a modified LCD production line, and that was the plan before the sale.
Now that Qualcomm owns the company, there's a good chance that Pixtronix screens will be made at the billion dollar production facility that Qualcomm is building in Taiwan. This was originally supposed to be used for making Mirasol screen, but given the similarities it seems likely that Pixtronix screen could be made there as well.