RE: alt text & punctuation - best practice?

Remember that the assistive technology has a responsibility here.  If the 
author has marked up the text as a heading <h1> or list item <li>, then it 
is the screen reader's job to add pauses, allow the end user to change the 
speaking style (i.e., louder for headings), etc.  In fact if we tell 
authors to add punctuation, incorrectly, then the screen reader will send 
that punctuation to the synthesizer along with it's own punctuation and 
you will begin to hear dot, comma, semi-colon, and colon as extra 
punctuation.  Look, if the screen reader doesn't pause after headings, 
then it is a screen reader problem.  All problems can't be solved by the 
author's mark-up or punctuation - that's why there is the User Agent 
Accessibility Guidelines [UAAG 
http://www.w3.org/TR/UAAG10/guidelines.html#gl-user-control-styles]

Please, please let's not advocate adding additional punctuation.  Semantic 
mark-up is enough.  Remember there is also Aural CSS, even though hardly 
anyone supports it. 

Regards,
Phill Jenkins