Ha! I posted that, went away, thought, "damn - someone is bound to ask about that, and it'll be Threadie...". It's basically about seeing literacy as a social and culturally defined practice (writing this on this thread makes me realise I was less of an empiricist than I thought); that the literacy/illiteracy dichotomy is essentially false (and yes, I know, duh, but in my field and others that came across as a fucking revelation to some, believe me).
Lots of work is done on "situated literacies" - so that the literacy practices you bring to reading a gas bill are not the same as those you bring to a novel; and these influence and are influenced by the physical setting of the text itself, and that's where my interest lay at PhD/postdoc level - examining not texts, but the physical nature of manuscripts to see what literacy practices could be understood from them, if that makes sense.
My putative proposal would be - and I'm not sure how it would work - to do a similar thing with the internet - pick a few sites, look at layout, access, printability, colour, language type, claims to actual or spurious authority, etc, and then do some audience analysis, etc. But I think it's (a) a long way off and (b) probably done. Also (c) I'm really fucking rusty at this stuff and (d) some bastard friend of ours borrowed my key texts and left them on a train...