UPDATE:
Visual Studio 2012 RTM still does not support creating/editing animations (via Objects and Timelines) out of the box....either in the accompanying Expression Blend for Visual Studio (which does not support WPF) or within the Visual Studio IDE itself.
However, there is a something called "Blend + SketchFlow Preview for Microsoft Visual Studio 2012" now available that is designed to work with WPF and Silverlight projects.
But it's only supported on Windows 7 SP1, and Windows 8.
It's version number is 5.2.30810.0.
In Visual Studio 2012 RC installed on Windows 8 RC 32bit, there doesn't seem to be an Objects and Timeline window anywhere.
And trying Blend 5.0.30514.0 it doesn't allow you to create or open WPF projects and have designer support....what gives?
How is one supposed to properly do WPF (i.e. capability to do animations/visual states) in .NET 4.5 with Visual Studio 2012?
UPDATE: Unless anyone else knows better you have to use multiple versions of Blend.
- use Blend 4 (4.0.20525 + SP1 4.0.20901) for WPF
- use Blend Preview for Silverlight 5 (4.1.20402) for Silverlight 5 only
- use Blend for Visual Studio 2012 (5.0.30514) for Metro only
Also when you open a Visual Studio 2012 project in Blend 4.0.20525 expect a warning.
I guess if you buy Visual Studio 2012 when it comes out, you'll have to try and buy an old copy of Blend to be able to do WPF development properly.