If you're interested in the arguments for and against the doom of eBook devices, have a look at
this entry in Charles Stross' blog. (though I'm guessing quite a lot of people have been over there.)
Short summary: he explains why he thinks that the market place will generally get swallowed by the phone/mp3/ipod touch devices as the volumes are too small, except for the high end professional markets where things like stylus scribbling are important. But he was surprised by the popularity of the PRS-505 amongst editors, so wonders if he has missed something.