I've served as Technical Editor for books on C#, LINQ, and Managed C++ or major publishers including SAMS, McGraw-Hill, and Manning. I've also held the position of QA Manager at a database company and other tech/marketing positions that (hopefully) qualify me to review and evaluate material for various audiences. If anyone at Telerik, Falafel, or anywhere else is producing a new book on RadControls, I would be honored for consideration to serve as TE for such an effort. A TE doesn't co-author or drive content. We go through all examples in detail, check the material for accuracy, and make suggestions on the flow of the content and suitability for the target audience. I tend to make notes on spelling, grammar, phrasing (colloquialisms and geekspeak) as well, even though the publishers have people to double check that. My position is that if you write a book, and guys like me are the target audience, and I "get it", then chances are pretty good that others in this audience will get it as well.
Michael's comments do point out the need for more/better reading material but I'll also note that books usually don't go through all of the nitty-gritty details unless it's like an "Unleashed" book with over 1400 pages. Personally I could really use more of those details too, lots of examples beyond those on the demo site. I think the demo site is more marketing material for people to learn the capabilities of the product. The examples seem intentionally uncomplicated, to avoid scaring away prospects. But we're drinking the Kool-Aid (so to speak) and need a lot more than what's there.
In the absence of a book provided by the few to the many, suggestions I've made here recently revolve more around allowing the community to help itself/ourselves, to produce content that we all need. While a book would be a great addition to the wealth of information available here, a book is also (almost always) a write-once event, and corrections, upates, and supplements are left to forums and second editions. We need something more "alive" than that. As one example, have a look at the PHP.Net site where almost every page of the basic documentation is supplemented by user contributions: http://www.php.net/manual/en/language.variables.php
If we could do that here, and I think this product is deep enough to where we need it, then we wouldn't really need a book. Hey, I'll take what I can get and I'll be happy to contribute when I can. I just want to keep as productive as possible, and if I can help others in the process it's a bonus.
BTW, since we're here, the product documentation on the website is obviously written by people who speak english as a second language. Please don't misunderstand - that's no criticism on the individuals - their english is much better than my bulgarian or russian! (Personally I prefer Esperanto anyway.) But when I'm reading the product docs I don't want to stutter on words and grammar - the material is already complex enough. This could also be a minor marketing issue. As my time and experience permit, I'll be happy to help improve those docs too and I invite someone from Telerik to contact me on the matter. Good docs is good for everybodies. :)