Miguel de Icaza made this statement on his blog. I wish he would elaborate. I have a few not very serious reservations about what little I know about Avalon at this point, but I am not seeing the simmilarity to j2ee. Is it just the complexity/surface area? If so, then I think the statment:

We will have to wait a couple of years for the "Rails" of GUI toolkits to come into existance. In the meantime programmers will pay for their sins.

is off by some years. Frameworks like rails are becoming commodity. Someone will have this out in no time. Just take the top off Monorail or add a new template for generating XAML views and some better tooling to the SCSF.

I would rather have rails for GUI apps than rails for web apps. Therefore Avalon on rails is a net gain to me, and others I'm sure.

I wish Miguel would elaborate a little.