Hello,
Yes, it can be used. WPF is a GUI library, so it is quite independent of the Graphics Mill for .NET. Graphics Mill for .NET provides very convenient conversion to the Windows native System.Drawing, so you can easily combine powerfull image processing of our library with new Microsoft GUI technology.
Of course, it will be very hard to use Aurigma.GraphicsMill.WinControls in WPF because they are based on the Windows.Forms controls, which are not intended to be used in WPF at all.
Actually we have such product which uses WPF for GUI and Graphics Mill for imaging - Aurigma PhotoKiosk. You can find more details and trial demo here:
http://photokiosk.aurigma.com/default.aspx.
Best wishes, Alex.