A friend and reader, Mike Lee, got his hands on an XO-4, and he posted this video. He got the XO-4 set up and then used the web browser to navigate to read.amazon.com to see if he could get the XO-4 to read Kindle ebooks.
This laptop runs Sugar, not Windows, Android, or some other commercial software, so there's no Kindle app for it. But thanks to Amazon's cloud based reading app Kindle Cloud Reader it is possible to read Kindle ebooks in the web browser.
Considering that this laptop was conceived as having minimal hardware which would sip at power, running a current web app is a pretty impressive accomplishment.
The XO-4 was originally unveiled this summer. While it looks much the same as previous XO models, it has an iR touchscreen from Neonode on top of the 8.5" Pixel Qi screens.
This laptop also uses the Marvell Armada PX2128 CPU, a faster CPU than on previous XO models. It also has 2GB RAM, 8GB Flash storage, an SD card slot, as well as 2 USB ports and an HDMI out port. That last port was added at the expense of one of the USB ports, and it was likely included at the request of teachers.