As a point release, there not a huge swathe of new features - the focus here is to open up the number of accessible platforms for developing on and developing for. Here's the change log from the official Windows Phone blog:
- The Visual Studio IDE is patched to enable selection from a list of emulators, and launching it (note that the WPSDK can only support connecting to one at a time, though).
- The Windows Phone [512 MB device] emulator image is updated to use build 8773.
- A second, new emulator device image is included, allowing you to emulate running your app on a 256 MB device.
- The Microsoft Advertising SDK is updated to the latest version (previously only available as a separate install), which fixes some issues devs were encountering at runtime.
- IntelliSense now supports specifying the 512 MB device requirement in your manifest file, should you choose to opt your app out from running on the new 256 MB devices.
- Language support is again consistent both in the IDE (the 7.1.1 Update supports all 10 of the WPSDK 7.1 languages) and in the emulator OS (Malay and Indonesian have been added).
There's more on the blog, and you can download your copy direct from Microsoft.