Hi all!
Thanks to Jonathan for a cool set of questions and to David for a great
response. I'm going to try to add my response to each question, but it might
take me a while! Everyone else chip in too please!
So....

Jonathan said:
1. There's no agreement about what the significant features of intonation are,
or what purposes they serve.

David replied:
I can't be sure about that, as I am only a becomming-phonetician, but I can tell
you that after have being shown the studies about English, Catalan and Spanish
TOBI, my opinion is that intonation is essencial in most cases. What about all
the possibilities you have in English with question tags, for exemple? I
discovered some really interesting things about my own language that I had not
realised before!

The problem is that intonation is really difficult of grasping as it touches
both Phonology and Phonetics... it can touch segments (phonemes) but at the same
time it is much more than that. In my culture we have a lot of gestures that go
with intonation, we can joke with it more than with changing sounds. ..

My tuppence worth:

I think there is a general agreement that it's bloody complex and so every
attempt to make it look simple will fall flat. One of the major problems is that
different researchers use very different definitions of "intonation", and that
makes comparison between studies difficult.
I don't really agree with any of the ELT definitions I've seen so far, so I'm
tempted to go with a broad philosophical definition like Bahtkin's (thus
including everything about how the expression sounds), rather than a tight
phonetic description of pitch change alone.

My related question is "Should TESOL models of intonation be phonetic or
phonological?"
i.e. Should they describe the contrasts that exist within English intonation in
an abstract sense?
Or, Should they deal with what the learners will actually hear with the full
crazy range of variation in how those abstract contrasts are manifested in real
speech?

Alex.