yeah blueZ is the official stack. seems to work quite nicely.
http://www.bluez.org/
I would also get the gnome bluetooth subsystem if using gnome
http://usefulinc.com/software/gnome-bluetooth/
you can then send files to your phone with something like
gnome-obex-push --dest <address> filename
you can use multisync to sync your evolution apparently
http://www.multisync.org
but i never got this working over BT
also you might find this FAQ usefull for setting up your fone, although again i had troubles with my 6600. Aprently works fine with 3650 and 7650 though.
http://www.bwestermann.privat.t-online.de/3650linux_en.html
Ive read rumors that people are reverse enginnering the PC suite protocalls but not seen anything come to light as yet....
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