Resolved! See edit at the end of post.
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I've made some progress. After installing gstreamer0.10-ogg and reinstalling ogg-support 3432423 time (mandatory, without it, installing gstreamer0.10-ogg doesn't do anything!), I got .ogg playback through mafw. OTOH, Theora still doesn't work, and tracker lost ability to see playtime of theora files. This time, error while trying to play Theora files is different - it complains that:
"can't find codec: Application/octet-stream".

This is very strange, as I'm almost sure, that before problems started, I had .ogg playback *without* gstreamer0.10-ogg package, and gstreamer0.10-maemo-xiph was sufficient. During IRC conversation, kerio confirmed, that .ogg is working for him, without -ogg and with -maemo-xiph. Could anyone else, who have working .ogg playback check own setup?

Generally, still no idea WTF...



Also, during the process of (re)installing everything back and forth, somehow, tracker again lost ability to see my .ogg and .flac files (despite both of them playing fine). Even better - while playing .ogg files, they work, but playback time isn't known and seeking is disabled. Even during playback, total time of track is shown as -00:01 second.

/Estel

// Edit
gdizzz, sorry for hijack thread As it's definitely mafw-related problem, not openmediaplayer one, I can move this discussion to separate thread, if it irritates You. I tried to ask here, as, You know, biggest chance of people knowing something about decoders on N900 (and initially, it wasn't sure if it's not OMP problem).
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Resolved!

// Edit

After 6 hours of fighting with it, I decided to nuke everything related to gstreamer, ogg, xipg, vorbis, theora, etc. After purging dozens of packages (as many others depended on xiph things, for example Marble), and reinstalling back again affected programs + ogg-support + extra decoders support, I've got perfectly working .ogg and .flac playback, with correct times, tags, etc, also visible by tracker. Theora wasn't playing yet (but playback time was visible), yet this time, responded with sane message about "lack of Theora decoder". Installing gstreamer0.10-theora and re-installing ogg-support again (to register it), enabled flawless Theora playback.

So, everything is working as it should Thanks to everyone trying to help. I have no freakin' idea, why it refused to work before - it seems that nuking this or that, sometimes, isn't bad idea, at all.