Some time ago in my post Books on beta versions - is it really necessary I said that I did not understand the point in publishing books about beta versions of technologies. I understand that the motive is to get the technology into the hands of developers as soon as possible so by the time it ships they can be sort-of ready to start using it.

Well, I changed my stance on this if just a bit. The original rant was mainly about ASP.NET 1.1 being current (at the time) and ASP.NET 2.0 being the new technology. Note the important thing here - 2.0 is an incremental improvement over 1.1, it's not fundamentally different.

When a completely new technology is in question, it will take a really long time for many to adapt so having a book early even if the content is slightly inaccurate should be helpful. Recently I gave in the urge and bought a book about Avalon AKA Windows Presentation Foundation. I shamefully admit that the main driver was not the reputation of authors (they have it undoubtedly) but the very good deal on a few other books I got from Amazon USA (I normally order from European, mostly French site as the shipping is free and fast).

Avalon changes many things developers got used to over the last 20 years or so. Old habits die hard and if you plan on switching soon  you should definitely start reading as much as possible. It's not just about the presentation, but about command routing, input and unified data-binding. Don't fear though - it's all logical, consistent and very clean. I find it a lot easier to author Avalon apps even without a GUI designer than to build WinForms apps, but that might just be me.

I am probably going to buy another book or two before Avalon ships because one of the authors - Charles Petzold - is very well known for his earlier work while another - Chris Anderson - is an architect on the Avalon team. At least Charles' book is supposed to come out slightly before if not to coincide with the final version. Judging by Chris' pace and his new hobbies I'd say his book will come out last :)

In short - books on beta versions are not useful if they are covering an existing technology's incremental improvement. If they are about a completely and fundamentally new technology, not only that it's smart to grab one as soon as possible, but you should probably get a few.