Hello.
I am happy to inform you, that the Audio Input pins of the iPod Touch are active,
and can be used for connecting any Audio source (like an external Mic, your CD-player, FM radio, etc) for recording. This also opens the doors for VoIP
applications!!
The way I tested it: Modded an old docking cable and connected the Line-In
pins to a source of Audio signal. Then used the Voice recorder App originally
written for the iPhone. The dock pinouts are here:
http://ipodlinux.org/Dock_Connector
I have photos of the setup if anybody is interested.
Cheers!