The tool has been around in beta, known as "wdist" for a few months. It was released today as plink 1.9 alpha: https://www.cog-genomics.org/plink2/
The usage is almost identical to plink1.07's. The main advantage of plink1.9 is speed. It also boasts an impressive list of accepted input formats and I have found it very good for general data management.
The homepage claims:
It uses a streaming strategy to reduce memory requirements, and executes many of PLINK's slowest functions ... over 100x (and sometimes even over 1000x) as quickly and even the most trivial operations tend to be 5-10x faster due to I/O improvements.
It certainly feels a thousand times faster for many operations.
It isn't completely finished yet so you might want to keep plink1.07 around for a few operations.
There are a few glitches here and there and not every single plink1.07 command is reimplemented, however the developer(s) seem to respond to and fix reported bugs incredibly quickly. And as the homepage says:
There are other additions here and there, such as cluster-based filters which might make a few population geneticists' lives easier, and a coordinate-descent LASSO. New functions are not a top priority for now (reaching 95%+ backward compatibility, and supporting dosage/phased/triallelic data, are more important...), but we're willing to take time off from just working on the program core if you ask nicely.
Linux, Windows and OS X versions available here: https://www.cog-genomics.org/plink2/
Note: I'm not involved in the project in any way.