Well I have a treo 650 smartphone/pda "thingy". I use kpilot for syncing etc to kmail/kontact.
yes it's usb, not serial. yes my "plug in lead" does have a sync button on it. I just plug the device in and hit the button for it too sync - the default sync seems to be a "backup", if I open kpilots GUI and use the drop down from "file" I can change this to a "full sync" so that when I hit the sync button on the lead, it sync's, backs up, installs anything I've told it too etc.
You might want to google for kpilot too find out if "they" thing that the M105 works with kpilot or not.