The IEEE standard for papers is still a two-column format, and the paper is only downloadable in PDF, so the first problem is that the paper is completely unreadable on anything other than your printed paper. PDF sucks, and therefore Kindle, ipad, etc. will all suck. This is totally fixable but I haven't seen an application yet that does it.
Other problem is that I like to literally draw on papers as I read them... to check the math, to call attention to something, etc. Nothing I have seen has as simple and easy to use of an interface as a pen and paper. Relatedly, when I desire to draw up a schematic or other technical drawing documentation, I have found that trying to do it on a computer is so complicated that it ruins my train of thought. It's not hard, per se, but compared with a marker on a whiteboard it sucks. Take a cell-phone-camera picture afterwards and it's preserved and digitized for ever.
Perhaps if Windows 8 takes off, and touch screens become the norm for all computers, and we can get rid of this ridiculous abstraction of a "mouse", we'll be able to accomplish more of these tasks on a computer. Still, for brainstorming or putting simple thoughts to paper, I don't know if I can see a future use case where the tablet takes over from pen and paper/whiteboard and marker. Unless doing it on a tablet adds something, it's just not worth it.