Wrox has recently published a new book by Wei-Meng Lee called Professional Windows Vista Gadgets Programming.  The second half of the book is dedicated to Windows SideShow development using the Windows SideShow .NET Framework Components (beta) release--a.k.a our managed API.  The book is a great introduction to Windows SideShow as well as gadget development, covering the major aspects of the API in C# and VB.NET, as well as the Simple Content Format (SCF).  There's even a comprehensive gadget sample included as well!

Happy readings!

- Dan