The changelog touts the ability to +1 a book while reading, in book search and landscape mode for flowing text on phones, and perhaps more interestingly promises better support for 7-inch tablets.
With the impending launch of the Kindle Fire and Nook Tablet, Google doesn't seem to want to be left out in the e-reading stakes. While there isn't a great deal of choice in the 7-inch tablet space as yet, it's still a nice feature to have included. Plus it'll work on your hacked Nook Color.
Download links after the break.