there are going to be a few tablet/slate type devices, the Notion Adam is very interestign but no clue when it will ship so it could be a year until it's done and shipping.
1.
Here is the Endgadget link.
2.
Here is a link to the MR thread about it
I forget the others but I also don't see many being ready to ship before March.
backlights are problematic as Harry pointed out. I actually prefer backlit readers and you will find many people also feel the same...so, make sure that your GF really does want a backlit reader. The thing about a device using an eink type display is reading it in the direct sunlight only makes it BETTER in fact for me, a LOT better.
I have two backlit devices in my old Clie PDA and a Nokia N800 Internet Tablet. Both are pretty nice. I can actually read the Clie in direct sunlight because it has a "transflective" display which reflects light back when you turn off the backlight.
The problem with buying any device that has a backlight and is not use a display without some form of transflective technology then if she wants to read outside, she won't be able to do so. But she can always add a book-light for reading indoors in poor ambient lighting or even the dark.
I would not buy any old device which cannot read the current formats or you will end up spending time learning how to format-shift and deDRM her DRM'd ebooks just so she can read them on that device. My old PDA is still OK because it supports MOBI format books but ePub, I pretty much have never even looked to see if there is a reader for PalmOS 5.0 which supports ePub...if you do end up needing to format-shift there is no easier tool than Calibre which was and still is being written by a member of MR...it has it's own forum...it's really slick software.
Anyway, read the news & comments section as well as visit Engadget to see a lot of info on what has been discovered and announced or even released at CES.
I wish I could recommend unconditionally a backlit reader but, to be honest, there have been none which stood out to me so far. I expect this to change as we see more slate/tablet like devices.
Something else is what will your budget be? Expect all of the tablets to be in the $200-$400 range...then again so are almost all of the eink type readers as well.
Just hang in there as info will keep trickling in over the next few weeks. I know of a couple devices yet to be announced from a company or two but neither will have a backlight.
Another question would be what size device would she be happy with? If she wants a smallish device then even an old PDA like one of the Clies or other PDA with a transflective display could be the option. Also, HP & Dell are joining the tablet/slate device market as well which will be backlit devices. And likely to not carry much of a brand premium because of the competition in today's market.