The same goes for the Japanese and Chinese fonts as well as the new font support for Simplified Chinese. (Remember how I said Amazon is opening a Chinese Kindle Store?)
Other improvements include better display options for Manga and more page refresh options. Amazon will also let you turn off the advertising (what you should read next) at the bottom of the Home screen, and when you buy a book after reading a sample, Amazon will now transfer your last read location from the sample to the complete book automatically and then remove the sample from your Kindle.
You can find the update at Amazon. It's going to be pushed out automatically.
On a related note, today's update confirms the obvious. Amazon isn't going to post any more updates for their previous touchscreen equipped ereader; the 2012 model has supplanted the 2011 model. Of course, this was so obvious that everyone should have figured that out, but apparently quite a few blogs felt the need to report it as news a couple weeks back. Go figure.