I've been trying to do more long form reading online, and it kind of sucks. Anything more than a page, and it get annoying. I've tried online books, PDFs, technical specs, long form comics, and its just not comfortable.
Short stuff is fine - though even long magazine articles are taxing...
I don't think its a tech issue, per se (resolution, rendering, or the like) - I think its a device form factor thing. One of the things I always really like about the swivel/arm generation of iMac was that it entered your plane... it wasn't distant in the way most monitor configurations are.
Its also very possible that its simply an age/comfort thing - enough effort and I'll get used it. Nevertheless, I think it contributes to the cycle of ever shortening attention spans.
On the flipside, it encouraged me to get a wireless printer, which I love and use regularly to read anything more than a few pages. I think somebody will get this right at some point - PDAs/phones are too small, and computers (even laptops) are too far and too ... not right.