F# Deep Dives, by Tomas Petricek and Phillip Trelford, Manning Publications
As many readers of my writing will already know, I've been kind of "involved" with F# (and its cousin on the JVM, Scala) for a few years now, to the degree that I and a couple of really smart guys wrote a book on the subject. Now, assuming you're one of the .NET developers who've heard of F# and functional programming, and took a gander at the syntax, and maybe even bought a book on it (my publisher and I both thank you if you bought ours), but weren't quite sure what to do with it, a book has come along to help get you past that.
As of this writing, the early-access (what Manning calls their MEAP) version had only Chapters 3 ("Parsing text-based languages") and Chapter 11 ("Creating games using XNA"), but the other topics ("Integrating external data into the F# language", "Handling dirty data with machine learning" and "Functional programming in the cloud" are just three of the other chapters listed) are juicy and meaty, and both Tomas and Philip are recognized names in the F# space. Neither are strangers to the subject material nor to writing, and the prose from the MEAP edition is pretty easy to read already, despite the fact that it's early-access material. In particular, the Markdown parser they implement in chapter 3 is a great example of a non-trivial language parser, which is not an easy task to approach but certainly a lot easier to do in a functional language. (For the record, I built a custom parser of my own for generating slides, and the blog entries that described the early implementations are here, and yes, I really should finish that series out, I know. I got more interested in extending the system, then realized I needed a full-fledged parser, and got distracted trying to integrate... surprise, surprise... Tomas' Markdown parser that he made available online.)
This book looks really promising, and I'm really hopeful Manning will send me a copy when it comes out, so I can level up my F# myself.