There's an unofficial extension to Ogg Vorbis to support loops. (note: I pulled it out of my nose...though I have a lot of audio in this format.) It consists of two extra comments in the Ogg stream, "LOOP_START" and "LOOP_END". LOOP_START is set to a real value corresponding to the time (in seconds) of the first sample "in" the loop, and LOOP_END is set to the time in seconds of the first sample "after but not in" the loop. The "looped" portion is samples LOOP_START through LOOP_END - 1 / samplerate inclusive.
Implementing playback of looped Oggs is easy, I have sample code posted here. (although thinking about it, it goes to a little too much effort... sample indices vs. sample positions and the like. Oh well.)
-:sigma.SB

TPG MUSIC ROXOR J00!!!

...is this a good place to ask for dynamic updates?? many times I've been chilling to the ambient greyspace music, only to realize I picked up an unbot or two on my tail...

..loops might pave the way for crossfading between tracks, and enable the audio engine to go "oh my, enemies!! better cue up the combat music!"

Umm. We have loops in the soundsystem. You know, like the engine noise, station noises, or anything else that loops continuously? They aren't ogg-specific, since we've supported other formats in the past.

What is it, exactly, that you would like to do with loops?

I think he's saying it's possible to mark up an ogg file so that it can have a loop embedded into it. So you could have a piece of music that plays through once, then loops whichever part is marked up (depending on what the program chooses to do with the loop info in the file).

So the music files could have some more interesting transitions between looped parts and such. Of course, that assumes new music files and all that.

Does that mean you want to use ogg files like basic tracker files?

Try playing this song in Vendetta. With the way Vendetta plays loops, you will hear the Lavos roar effect every 3 minutes, not to mention the drum cutting out at the end. Taking into account the embedded loop, it loops nicely, with Lavos roaring only once, at the beginning...
That song doesn't really fit Vendetta, but it's the best example I could find.
-:sigma.SB