Just to report success on Debian/Linux-2.4.20, with usb-uhci module, and HP Jornada 565.
It was compiled and installed according to http://synce.sourceforge.net. The only question I had was with the synce module; it is still present in the cvs tree, and it is not needed by now.
I could create a new directory "Linux", but after issuing the command "pmkdir Linux", the new directory doesn´t list with pls. (It really existed in the PDA). I could copy some files to this new directory from my laptop to the PDA, but not to any other directory.
I will do more tests next days.
Thank You.