It came to my attention while approving submitted links the existence of two Linux Bluetooth stacks.
The first one is BlueZ, the Official Linux Bluetooth protocol stack. It is an Open Source project distributed under GNU General Public License (GPL). BlueZ kernel is part of the official Linux kernel since version 2.4.6. BlueZ was originally developed by Qualcomm Incorporated.
Supported on BlueZ:
Bluetooth Core (HCI device and connection manager)
HCI USB, UART, PCMCIA and VHCI (Virtual HCI) drivers
L2CAP
RFCOMM
BNEP
SCO
The BlueZ user space packages provide support for:
SDP (Service Discovery Protocol)
PAN (Personal Area Networking)
LAN (LAN Access over PPP protocol)
The other package is a Bluetooth Protocol Stack for Linux developed by Nokia Research Center in Helsinki and released under GPL. Its name is Affix.
Supported on Affix:
General Access Profie
Service Discovery Profile
Serial Port Profile
DialUp Networking Profile
LAN Access Profile
OBEX Object Push Profile
OBEX File Transfer Profile
PAN Profile
According to the homepage, Affix was tested for interoperability and worked ok with:
Nokia Bluetooth Phone 6210 with Bluetooth battery pack,