Kindle -ready for action?

I've been keeping an eye on this e-reader malarkey. As much because I spend about 7 hours a week on trains and don't want to carry more weight in books than I have to; this kind of device would seem to be a potential help in my on-train reading to weight ratio! I am also keen on the e-ink idea because back-lit screen can't do well in very well lit positions and sometimes a train seat by the window is exactly that! I'm also of an age when holding a book's weight for extended periods can give rise to concerns about carpel-tunnel problems and RSI, so a lighter device with no concerns about positioning oneself to hold pages open is a definite plus.

However, I have other concerns. Ones I think are probably shared be those involved in scholarly pursuits. I need a device that allows me to annotate the text, highlight stuff for later retrieval and in general enable me to re-cycle stuff into further articles and arguments. It seems that the Kindle would enable this to happen: : "using the QWERTY keyboard, you can add annotations to text, just like you might write in the margins of a book. And because it is digital, you can edit, delete, and export your notes. You can highlight and clip key passages and bookmark pages for future use."

What I don't know, though, is how many formats of e-books there are and how versatile the Kindle might be with regard to them, and whether there are other devices that would get a greater thumbs up ... Anyone got any suggestions or any more thoughts?
Kindle Wireless Reading Device, Wi-Fi, 6" Display, Graphite - Latest Generation: Amazon.co.uk: Kindle Store