A few months ago, one of the developers in the V4L (video for linux)/DVB (digital video broadcasting) team, AnttiPalosaari, discovered that this cheap video tuner dongle could be used as a software defined radio. Since then, it has developed a HUGE following! The team over at osmocom helped to package the driver into a separate executable. The application seems to work well, and even compiles on the mac. The problem is that you have to install the libusb library for it to work. It's not hard to do, but you have to install mac ports, then install libusb. What a pain.
Most of the active discussion about rtl-sdr appears to be happening at the RTLSDR subreddit.
The idea behind Softshell is to port the osmocom rtl-sdr code into a native Cocoa application that doesn't need libusb. I've published the code to gitlab, but it's still very early in the development process.
This post is just meant as a heads-up for anyone with Objective-C experience and an interest.