Okay, yeah, now I think I see what you're saying, Zeek, sorry to be so dense.
In Acrobat 7, under the Advanced menu item, is an Accessibility item, which has an option to add tags. (if that's not what you mean, please point me in the right direction

) I didn't know that an
existing PDF could be tagged like that, thanks for pointing it out.
In any case, I agree (already did, in fact) that if the PDF viewer that Sony put on the Reader could handle PDF files that were tagged for reflow, it'd be a huge improvement, even bigger than I previously thought, since existing PDFs can be tagged.
As RWood has confirmed (and as you were saying in the first place) the Reader doesn't seem to care, or indeed notice, that the doc is tagged for reflow.
I know that the Adobe Reader I have on my Pilot handles all that automagically, it'd be nice if the one on the Sony would do so too.
Perhaps they could have the M size setting go to the reflowed display, and leave the S and M doing what they do now, so that folks could still see the layout if they needed that for reference.