I am going to make my answer a little broader than DWTs/c# TBBs and instead address the wider availability of study materials for Tridion 2011.
As Nuno mentioned, there are not any books like the Wrox Professional series of books on .net for SDL Tridion.
However, in addition to the documentation on SDL Live Content Nunos has linked to in his answer, there are a number of other types of reference sources where you can pick up a good bit of knowledge on the inner workings of Tridion especially if you are willing to dive into a little bit of other people’s code.
First, I would suggest taking a look at the many community created blogs listed in the question List of SDL Tridion References as many of the postings on those blogs go into specific issues the authors have encountered in the course of their day to day work with Tridion and how to solve the issues.
Additionally I would suggest taking a look at the source code for the Tridion 2011 power tools project found at http://code.google.com/p/tridion-2011-power-tools/, the source code for the Dynamic Delivery 4 Tridion project found at http://code.google.com/p/dynamic-delivery-4-tridion/ and the Razor Mediator for Tridion project found at http://code.google.com/p/razor-mediator-4-tridion/ .
They all provide a fair amount of insight into how to use different parts of the Tridion stack such as core services and the tom.net API.