C# 3.0 Design Patterns by Judith Bishop.
This is a good rehash of the Gang of Four patterns, reworked in C# 3.0. The book's fairly concise and most patterns are clearly laid out with a simplistic example to demonstrate the basics of the patterns followed by a more detailed example in a semi-real world implementation.
The articles are nicely done, there are a good set of exercises about each pattern, and there are some good comparisons between similar patterns. As an example, there's a bit comparing the Builder and Abstract Factory which details that a Builder is concerned with how things are built while an Abstract Factory is concerned with what is built.
A couple things bothered me in the book, namely the lack of a clear overall summary of patterns, and an annoying batch of sidebars on fairly basic concepts. While each pattern has a summary of when you would use it, you're forced to dig through the entire book looking at each pattern trying to figure out if it will solve a problem for you. A consolidated list of the uses of each pattern at the start or end of the book would have been a great help. Regarding the sidebars: do I need a patterns book to lay out fundamental concepts like accessibility modifiers or indexers? These detract from the book's main purpose, which isn't to teach C# 3.0, but show how patterns are done in C# 3.0.
Those annoyances aside, I found the book to be a good read and a useful addition to my bookshelf.