there are a lot of cool things covered here, but the two most striking ones are the coverage of Message Queues and Security.

I just got into advanced messaging and there's not a lot of documentation out there. If you want to learn it, you used to have to stumble around until you got it right. Their coverage of the subject changes all of that. It explains messaging in depth and has many practical exapmles. In addition, it walks you through many of the common 'gotchas' you'll encounter when developing message based apps.

Another great area is security. I know in my experience, I was too busy learning .NET to really focus on security. That's like being in too much of a hurry to put gas in your car. i wish I would have realized this earlier. They discuss just about every practical aspect of security and have a lot of great examples as well.

These are my two favorite parts of the book, but there are many more. They explain Regular Expression for example and have tons of useful examples in it. They have a great GREP utility example that just about any developer will really enjoy.

I've bought Petroutsos' other book and really enjoyed it...and history repeated itself with this one.