What books do you recommend for programmers?
The most comprehensive book about PowerShell is still, without a doubt, Windows PowerShell in Action by Bruce Payette (one of the original language architects). The Third Edition is available now, with updates by Richard Siddaway. It's published by Manning, so there are a couple of free chapters on their site.
- Windows PowerShell in Action, Third Edition - Manning Publications
- Windows PowerShell in Action, Third Edition (via Amazon affiliate)
What books do you recommend for .NET developers?
If you're a .Net developer that's trying to learn PowerShell, you might also have a look at Windows PowerShell for Developers, by Douglas Finke -- it's full of scripts that you can relate to, and that will help you learn to embed PowerShell in your apps for scripting, automate task in development, and interact with .Net and native DLLs, COM, etc.