You can download the latest version of JMPalm here.

Also available is JMC (JuggleMaster Pattern Converter) which allows you to convert regular JuggleMaster pattern libraries (e.g. patt_e.jm) into a format JMPalm can use. Note that the download of JMPalm includes Isaac Orr's pattern library which includes 372 different patterns.

Download JMPalm for Palm OS version 1.3.0
Download JMC for Windows 9X/ME/NT/2000/XP version 1.0
Download JMC for Linux glibc precompiled version 1.0
Download JMC source code version 1.0

If you have problems running the latest version, you can try the old version 1.1 instead:
Download JMPalm for Palm OS version 1.1.0