Application Code Blocks are little “parts” of programs that Microsoft has created that you can install, and then include the assemblies in your program. The code has been tested and was created with best practices in mind.
We went over:
1) Configuration Management Block : Allows you to set up app.config files easily and encrypt and sign them. This is really cool so you can have settings in a file for your program and keep them secure, while not having tons of code to manage
2) Application Updater Block : Have you ever ran an application that popped up with a box that said there was a new version and that you could click yes to update it? This code block makes this about 100 times easier. You can include the code block, and set up a manifest on a web server, and your program will auto update!
Steve Novoselac's Blog 