Version 2.0
Here you can find a description of some new features/breaking changes/bug fixes of the new AvalonDock version (2.0).I've rewritten AvalonDock 2.0 from scratch using a MVVM approach. In short there is a deep separation between the Model (that describes how the layout is composed), the ViewModel (which prepares the model to be consumed by the view) and the View (a set of stylizable controls that show the user controls).
Binding Issues
Version 1.* suffers of an annoying issue regarding binding that doesn't work for flyout panes and floating windows (for a detailed description of the problem please read Binding Issues. The problem here is that wpf logical tree is broken when a content is moved inside another window (like when user move a pane in a floating window).
Version 2.0 fixes this problem definitively.
Flyout windows perfomance
In version 1.* when a user put a content in autohide state a new window is created by AvalonDock. This windows must be synched in position and size with the docking manager. This leads to a perfomance issue because involves a lot of interop.
Version 2.0 use the same mechanism of VS 2010 (child windows with redirected logical tree) to show autohide windows increasing perfomance and stability.
For more info http://blogs.msdn.com/b/visualstudio/archive/2010/03/23/wpf-in-visual-studio-part-5-window-management.aspx
Floating Windows Aero Snap
Version 2.0 will support Aero Snap (http://blogs.msdn.com/b/visualstudio/archive/2009/11/05/tips-and-tricks-window-management-aero-snapping.aspx).
Floating Windows Integrated Docking
In Version 2.0 you'll be able to redock a dockable content inside a floating window (as happen in VS2010).
Focus and Activation
I'm working to mitigate/eliminate all the focus/activation problems that causes a lot of headache developing with version 1.2. This is what I've in mind (why not learn from masters :) : http://blogs.msdn.com/b/visualstudio/archive/2010/03/09/wpf-in-visual-studio-2010-part-3-focus-and-activation.aspx
Layout Serialization
In version 2.0 layout serialization/deserialization is much (much) more easy because layout is a model completely separated from the view. This will allow an easier integration with framework like PRISM/MEF.