Major_Payne - 2:59 am on Sep 8, 2010 (gmt 0)

the SE's will happily read the alt attribute value and use it for header tag content.

That's an important point, but I have noticed too many pages that have an alt="" attribute that is blank just so it passes the validator.

With no text, SEs will miss it. Others put in badly worded text which IE wrongly displays as a tooltip on a mouseover and SEs will not make much sense of. It might be better to include the title="" attribute along with the alt="" so other browsers can correctly supply the mouseover tooltip and the SEs may take more notice of the "heading" text within the title attribute than the alt.

Of course, the title="" can be put in the image or the heading tag.

Sorry if I appear hard-headed about all this. Guess I am a code-nazi. :P