A couple years ago I asked if there was a clear winner between a Kindle Fire and B&N Nook Tablet. It turns out there is now, as Barnes & Noble announced they will no longer manufacture color Android-based tablets and instead focus on their core business of eReaders.
Amazon came out with the Kindle Fire at a time when the iPad was really the only successful competitor in the tablet space. Today, we see low-cost Android tablets all over the place, including $99 models available at Wal-Mart, and Barnes & Noble's financial results show it is tough to compete in that market with the Nook HD and HD+.
B&N stated they do plan to work in partnership with third party manufacturers to co-brand color tablets, but we will have to wait and see how that turns out.
If you visit the B&N site right now you can see the Nook HD is available for just $129 (regularly $199) and the Nook HD+ for $149 (regularly $269) so if you have been thinking of one of these devices, now might be a good time to pick one up before stock runs out.
In addition to being the first ebook company to launch a color reader/tablet device, I think a lot of Amazon's success is also due to their media and shopping ecosystem. The Kindle Fire is attractive to Prime members because of free video streaming, and because shopping through the full Amazon store is made easy on a Fire.
If you want to read ebooks, then nothing beats an eInk display device, so it makes sense that a bookseller is going to focus on that market and see what develops in the color tablet market in the future.