I got my hands on a Kindle a year back, and it just opened PDFs and text documents I put on it using it as an USB drive. Amazon even provided an app for rolling your own Kindle-format ebooks from hypertext files, which you could again just plop on the Kindle over USB.

My main problem was that the regular Kindle was too small for viewing technical article PDFs full screen. I can already use my smartphone for reading stuff that's easily reflowable, like most fiction. The Kindle DX should be better for this, but I haven't had a chance to try that.