Yes, JPD runs under LINUX :-)
And here is the HowTo.

You need:
LINUX :-)You already have it, right?
Java for LINUXUse IBMs JAVA VM 1.1.8 for the fastest results (it's realy pretty fast, believe me)
COMMAPI for LINUXYou need to get the SOLARIS version.
JCL for LINUXYou need this Library if you want to HotSync with your Palm (aka Pilot).
JPD itselfYes, you really need this :-)

1. Install the JRE/JDK

IBMs JRE: (preferred)

Blackdowns JRE:
Read the README included in the Package.

2. Install the COMMAPI

t.b.d.

3. Build and install the JCL (Java Comm 4 Linux)

t.d.b

4. Install JPD, if not already done

Now you can start JPD by typing jpd in a command shell.
If you are using KDE (like I do), go on with the next steps:
Now you can start JPD by clicking on the object of your Desktop.