I am investigating this as well. Few things I discovered:
I brought a SD card with various ebooks in to Costco to try out the Aluratek Libre Pro... it's great! It's NOT eInk, it's TFT (LCD). You really have to see it to realize this is a good thing. Check out some of the YouTube videos for this, the screen looks really clear, you can see the page clearly even though they're waving it around in the videos. EDIT: I should mention it opened epub, non-DRMed PDF just fine. The ePub could be a little sluggish to open, but PDF was fairly quick - I think it opens it in chunks, so page turning won't be as quick.
The Jetbook Lite looks great too, but needs some work on the firmware so it doesn't crash hard with rechargeables.
The Sony Reader wouldn't read the same SD card - it may be more picky about how things are laid out on the card (I pulled it from my n800 at the store).
Google for ADEPT DRM and check out the I (heart) cabbages blog post, it's really interesting. Some readers even support Adobe DRM so I could take library books out.
Baen.com Free Library rocks! Even their non-free ones are cheap, like $5
iTunes has TONS of O'Reilly and MS Press books for about $5 too, with no DRM, so even if you don't have an iPod or iPhone you can extract the epub ( they even explain how,
here )
I am sure I will have a reader before the summer, or at the latest, by camping season. I'm loving ebooks so far, and I have only been using non-dedicated readers so far.