Two weeks ago I announced new maintenance release of JSON UDFs: 0.2.1. It not only contains bug fixes, how you can expect from a maintenance release, but also contains improvements in build and test scripts.
First improvement is the easier way to build JSON UDFs on Windows. In the first version building on Windows was a pane: you had to build PCRE library, copy four files to directories where Visual Studio can find them and only then build JSON functions themselves. Now you can build this way too, but only if you really wish.
By default cmake will create appropriate makefiles for bundled PCRE sources and for JSON functions. Only command you need to prepare sources is:
"C:\Program Files (x86)\CMake 2.8\bin\cmake.exe" -G "Visual Studio 11 Win64" . -DMYSQL_DIR="/path/to/mysql/installation"