We have made a few changes to the Ads API .NET client library to allow better maintenance and support.
Unified repository
For ease of maintenance and to reduce duplication, we have combined the 
AdWords, 
AdXBuyer, 
DFP and 
DFA API .NET libraries into one repository: 
https://github.com/googleads/googleads-dotnet-lib
Going forward, please use the new repository for downloading Ads API .NET client library releases, reporting issues, requesting features, and providing source contributions.
We have updated 
wiki articles, consolidated 
open issues, and 
imported source code of past releases.
New runtime requirement
We have increased the runtime requirement for the client library to Microsoft .NET Framework 4. This upgrade allows us to enhance the library using features available in newer versions of the Microsoft .NET framework, while moving away from .NET 2.0, which is past its 
mainstream support period.
In case you are still using Microsoft .NET Framework 2.0, you may continue using the 
legacy library until 
July 1st, 2015, at which time we will stop providing bug fixes and enhancements to the library. Major feature enhancements and support of newer versions of the APIs will be limited to the newer library that uses Microsoft .NET Framework 4.
Updates to version numbers
We have updated the version number of the Ads API .NET client library to 
18.0.0. The Common library version has been updated to 
3.0.0. Going forward, all the API-specific client library assemblies will share a single version number, while the Common library will continue to maintain its own version number.
The legacy library assemblies will only have minor releases, and will use the following versioning scheme on both Github and Nuget:
  - Google.Ads.Common: 2.x
- Google.AdWords: 17.x
- Google.Dfp: 7.x
- Google.Dfa: 5.x
If you have questions or feedback, let us know on our forum or our 
Google+ page.
 Anash P. Oommen, Ads Developer Relations
 Anash P. Oommen, Ads Developer Relations