"Learn bits about N900 sound thingie's", you ain't kidding. The GStreamer mechanism is vast; I spent an amazing amount of time researching, selecting components, and twiddling with parameters before I managed to record a single audio file. And I suspect you could spend a lifetime trying to come up with an optimal GStreamer pipeline, there are just so many variables to consider... And, as it turns out, I didn't understand DBus nearly as well as I'd thought either.
Anyway, after much teeth-gnashing and hair-pulling, I've come up with a rudimentary audio recording app. It still needs work, but I figure I should put it out there and see what folks think about it. I've named it "Orecchiette"; I'll go ahead and put up an announce thread for it...
I'm still working out the details on how audio actually works. I've currently got SPX, AAC, WAV, and FLAC encoding options set up, and they all seem to be working. I dunno if MP3 will work, there are patent encumbrances on it; but there might be a Nokia MP3 plugin available... Is "OGG" actually an audio encoding? I thought it was video. Let me do some research. EDIT: Ah, yeah, "OGG" is the mechanism used for packaging audio and video together. (Kind of like Matroska.) There are several open source audio formats; I've already got support for Speex (an encoding format optimized for voice data). There's also Vorbis and Opus, which are higher-end encodings for music. Dunno just how much of a load using those would place on the N900, though.