Gnome-pilot looks like a good answer – but only if you want to use evolution.
First, gnome-pilot is a gnome product, as is evolution. Thus, I believe, that gnome-pilot will only work with evolution, not thunderbird.
http://ubuntuforums.org/showpost.php?p=6200523&postcount=3
I ignore the standard “built-in” Palm app under Ubuntu, namely “gnome-pilot” – although it does work well and has a wizard set-up etc. It integrates well into the default organiser (PIM) environment in Ubuntu/Gnome (evolution).
I tried evolution and I don’t like it… not because it doesn’t work.. it does, quite well…. I prefer to use Mozilla Thunderbird for email.
If you want to try it (in Ubuntu) go in the main Gnome menu to “System -> Preferences -> PalmOS devices
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So… What do I use…?
I use jpilot.
This is a (kind-of) Palm Desktop clone – with the 4 main apps (datebook, todo, memo, address book).
http://www.palminfocenter.com/forum/viewtopic.php?t=34701
JPilot works fine but it gives you the equivalent of the Pilot interface. So no easy integration with Thunderbird that I could find.
In either case you need to connect via usb:
At the Device Settings screen, click the radio button for USB and then click the down arrow at “/dev/pilot”. Select “usb:” from the pull-down menu. Older instructions are different but I think newer versions of Ubuntu use usb: now.
JPilot works fine though if you press the sync button on the Palm device sync cradle first and then the sync button in JPilot a second or so later. Bidirectional synchronising of calendar appointments etc.
If you don’t do things in the right order you might get an error containing: “Exiting with status SYNC_ERROR_PI_CONNECT” (See http://www.linuxquestions.org/questions/linux-laptop-and-netbook-25/unable-to-sync-palm-tx-with-j-pilot-406142/#post2640531).