Microsoft's own .NET package management tool, NuGet, has been upgraded to version 1.2. This release is an iterative improvement on the previous few releases. NuGet competes with the open-source OpenWrap package manager, which also supports version 1.1 NuGet packages.
The new NuGet release implements a number of improvements across the board. It is now possible to include assemblies in packages that target a specific profile of a framework. Where previously you may have only been able to target .NET 4 or Silverlight 3, you can now target profiles of those frameworks, such as the Windows Phone Silverlight 3 profile.
It is now also possible to specify within package configurations which framework assemblies will be required to use the package. For example, while various assemblies will be required inside the package itself, there may also be framework assemblies the developer will need in order to use the package.
As ever, it seems, there are some breaking changes with this release. Packages built with NuGet 1.2 won't work with the version 1.1 and below client. Old versions of the NuGet.Server project are also now broken and will require an update to restore functionality. You may also still run into the broken signature issue if you happened to download a previous NuGet version which was signed with the wrong certificate.
If you already have NuGet installed, you can get the new version by simply upgrading inside Visual Studio 2010.