ARIA Question

I really, really like the work that's been done on ARIA so far, and I think
it's going to make a huge impact on accessibility.  To me, the best part
about it is that it doesn't seem to require applications to be re-written to
take advantage of ARIA: for the most part it looks like I just "decorate"
existing markup with the new ARIA attributes and I'm done.

There are a lot of web applications that (for one reason or another) use
tables to lay out their interface.  I was thinking specifically of
SharePoint when I started out, but I just inspected GMail's DOM, and sure
enough, it's tables all the way down.  Flickr seems to be structured the
same way.  Have you considered defining something like a "layout" role that
could be used for <table> tags that don't contain tabular data?  This would
tell screen readers which tables should really be read out as tables, and
which ones should be ignored.  If not, is there something already written
into the ARIA draft that would accomplish the same thing?

I've heard a whole lot of campfire horror stories encouraging me to always
use semantic markup and never use tables for layout; most of these center
around the idea that screen readers announce tables as they read through the
page, interrupting the content and making everything take longer.  If the
tables-for-layout problem really is as bad as people make it out to be, and
a simple fix like a "layout" role really could improve the situation, then
it seems like it's worth pursuing.