I've noticed that the new version of WordPress inserts tags
when one does a line break now. I don't remember ever seeing this in older version. I just tested this with WP 3.0.4 and you weren't able to do this before.
I'm not sure if this is a bug or a new feature. Anyone know?
Interestingly, I'm seeing this at the END of SOME of my posts. Clearly more research is required :)
(I never noticed it before 3.1.3 because I never used the visual editor regularly before now).
Just tested briefly with WP 3.2 and looks like there are no more line breaks. Something buggy must have been introduced by TinyMCE in version 3.1.