However it's not just screen reader users that find having content first on the page useful: mangers do, too. Why? Well, it's not because most managers use lynx to browse the web, it's because most managers like to see their sites having first page rankings on search engines.
Now, this article is by no means going to give readers 'the secret of number one search rankings', but it is going to describe how the playing field will become level.
There are only a few 'tricks' that need to be learned in order to optimise your site for search engines, and, currently, they are almost identical to those needed to make your site accessible. It's only a matter of time before either the majority of websites learn these, giving a level playing field, or search engines change their methods of ranking sites completely (which could happen next week, for all we know).
Of course, getting your content first in the document flow isn't the only thing you need to do (technically and otherwise) in order to optimise your page for natural search. There are many other factors, including linking, both within, from and to your site, and based on the 'quality' of these links (the authority and page rank of the linking pages) and, indeed the keywords on you page and the form and quantity of the copy.
These you need to work on seperately.
There are, however, several simple technical things you can do in order to make sure your page is search engine spider friendly and search engine friendly. Once these are learned we have the level playing field, and the quality of the site and popularity/authority of the site come into play, however these are measured.