Like it or not, ereaders are definitely a huge part of the future of books, especially for business travelers. With an ereader you can take hundreds of books with you on a trip, you can write notes, underline passages, and it all fits in a package smaller than typical paperback book. Pretty nifty.
In late 2011, Amazon released a number of updated Kindle ereaders, including its most basic version (simply called 'the Kindle'), the Kindle Touch (which adds a touchscreen), to the new, slick Kindle Fire (read the full review of the Kindle Fire). Amazon continues to sell the previous versions of the Kindle as well (reviews of the Kindle Keyboard and the Kindle DX).
For an overview of the complete Kindle line, check out About.com's Guide to Portable Electronics complete guide to Kindles.
The new, basic Kindle is a great deal for an ereader. It's lighter and thinner than Amazon's previous Kindles and fits easily in your back pocket (but you really don't want to keep it there--it's too easy to forget about it and sit on it!). It has a basic push button navigation and traditional forward/backward buttons on the left and right sides. Although my existing Kindle works fine, I'd love to upgrade to this nifty little package.
The new (Fall, 2011) Kindle is Amazon's entry-level ereader. Unlike some previous Kindles, it only has Wi-Fi connectivity, and no cellular connectivity (which enabled the original Kindles to download books or access the Internet even when you weren't near a Wi-Fi connection). It has a basic five-way push button controller for navigating menus and documents.
The unit has a 6" inch E-Ink screen, which provides a very crisp reading experience. However, since (like other E-Ink readers) the screen isn't backlit (like tablets or the color Kindle Fire) it will require an accessory book light if you want to read in darkened areas (the bed, on a plane, etc.).
The basic Kindle comes in two different versions. One is an advertising-supported version, and the other has no advertising. The advertising consists of screensaver advertisements and advertisements that display on the bottom of your home page. They frequently offer local deals, in addition. I would personally recommend the advertising supported version. Not only is it cheaper, but the screensaver advertisements are frankly more appealing and changing than Amazon's unchangeable screen savers. (For some reason, Amazon refuses to let customers delete or change the screen saver on the Kindles. I understand that on the advertiser supported models, but it makes no sense on the traditional models.)
Prices are competitive. The basic model (advertiser supported) goes for $79, while the advertising-free version retails for $109 (still a great deal).
Battery life is listed at one month, although I've exceeded that on previous Kindles. These machines can stay charged for LONG periods of time, if you turn off the Wi-Fi connectivity.
Just like previous Kindles, text size is adjustable, books download in seconds (over Wi-Fi), and it can hold more books than you can read on a business trip.
Amazon's also added a number of benefits for Kindle users, including support for public libraries (check with your library to see if they support Kindle versions), free cloud backup, and a new Kindle Lending Library that includes both current and older books for users to borrow.
I'd love to have something negative to say about the Amazon Kindle, but it's hard to find anything. Perhaps the only things I can note are that this version doesn't include a physical keyboard (like the older versions did), so that entering text (like when you're searching for a book in the store) takes a little extra effort, but it's really not that bad once you get used to it.
The other aspect to note is that the basic Kindle doesn't include the text-to-speech capabilities of some of the previous Kindles, although I personally never used them and don't miss them. You also can't download Audio books, but again, that's not something most people will miss.
Recommendations for Business Travelers
The Kindle (basic edition, advertising or no advertising) is a great option for business travelers. It's small, light, stays charged for long periods of time and is a treat to read on. This is a slick little machine.
If you want to do more than simply read books (or magazines) on it, than I'd recommend considering either an iPad, a tablet computer, or the Kindle Fire. All of those provide bigger screens (at least 7" usually) and color displays. They're all heavier and more expensive though, and don't stay charged anywhere near long enough.
If you're thinking about an iPad or Kindle fire, check out five reasons why the Amazon Fire is no iPad killer by About.com's Guide to iPads. You can also read my review of the Kindle Fire.