The Source profile is what enables the A2DP bluetooth profile. With it, you can use your system as a stereo audio output device: in other words, you can send output audio from an external device such as a phone or a tablet to your computer (though this will require a bit of work on the PulseAudio side to get the audio stream to go through the right devices).
There's the AskUbuntu question "Can I use my computer as an A2DP receiver?" that describes the steps to use this right now. Thanks to Steve Langasek for figuring out the details. I've also written a draft script that implements the suggested steps and makes it simple:
#!/bin/sh
BTSOURCE=`pactl list short sources | grep bluez_source | awk '{print $2;}'`
SINK=`pactl list short sinks | grep -v Monitor | grep alsa_output.pci | awk '{ print $2; }'`
case $1 in
enable)
pactl load-module module-loopback source=$BTSOURCE sink=$SINK
;;
disable)
pactl unload-module $(pactl list short modules | grep loopback | grep $BTSOURCE | cut -f 1) || true
;;
esac
That script is meant to be called as '"whatever_you_named_it" enable'. Don't forget the "enable" part, or "disable" to turn off the streams, otherwise it won't work.
The Gateway profile enables the HSP/HFP bluetooth profiles. This means we're getting closer to supporting phone calls from a bluetooth-connected phone on a Ubuntu computer. There's already some amounts of support for this via Ofono and the telepathy-ring project, although there is some extra work needed -- hopefully we can fix this by the Precise release. :D
