Get a list of updated fields in Model.update?

Is there a spiffy Rails way to easily get a list of fields updated in
an update call? I figure it's possible to go into the model and keep
track of what fields are changed in each field=() method (before the
save happens), but I'm hoping that there is a method that will do that
for me. Any ideas?

Thanks.

That's exactly what I'm looking for! Thanks!