Although they were released in 2007 (Linq-to-SQL) and 2008 (EFv1), these two data access technologies and the tools, frameworks, and language features surrounding them are new to lots of people who are just about to start using them.
The following blog post covers some resources (books, blogs, forums) that contain everything you need to get started with and/or understand how Entity Framework, Linq-to-Entities, Linq-to-SQL, or LINQ in general works.
Books and Blogs
Professional ADO.NET 3.5 with LINQ and the Entity Framework by Roger Jennings covers all the new data access technologies that were introduced with .net 3.5. Roger has written 30+ books on everything from operating systems, databases, programming, data access etc. Nowadays he is covering cloud computing in his blog and in his latest book.
Before his interest for cloud computing took over completely, Roger covered just about everything that happened in the .net data access world (Linq-to-SQL, Linq-to-[everything else], Entity Framework, ADO, etc) with daily updates in his blog,
http://oakleafblog.blogspot.com/. All those L2S/EF/ADO articles are still there if you scroll down a bit, and links to lots of useful code samples and tips and tricks.
Programming Entity Framework, Second Edition and The Data Farm
Julie Lerman has written two books on Entity Framework. The first one covered EFv1, the first version of Entity Framework that shipped with .net 3.5 SP1.
Her latest book, Programming Entity Framework, Second Edition, is for Entity Framework 4 or EFv4 that shipped with .net 4 / Visual Studio 2010. Programming Entity Framework, Second Edition is 914 pages covering every little corner and aspect of EFv4.
Julie has a couple of blogs to go with the book:
…and she also writes the Data Points column in MSDN Magazine.
Linq in Action and ThinqLinq
Jim Wooley also has a blog with lots of useful Linq tips, tricks, and solutions at http://www.thinqlinq.com/ . His blog also has a page with links to various third party tools for L2S and EF:
Damien Guard used to work with the Linq-to-SQL and Entity Framework team at Microsoft. Now he is working with some other team at Microsoft (XBox..?). His blog has a lot of L2S and EF goodies, among those a neat one-page reference to the most commonly used Linq syntax. Very handy to have on the wall when writing code against Linq-to-SQL or Linq-to-Entities: http://damieng.com/blog/2009/08/12/linq-to-sql-cheat-sheet
Damien also has some links to various Linq-to-SQL resources; tools, blogs etc:
The MSDN forums, run by Microsoft, is a gold mine of useful information on both EF and L2S. Just browsing/searching these forums can reveal a lot of useful information, best practices, tips and tricks etc. If you can't find what you're looking for, post a question and you will probably have a solution within a day.
StackOverflow also has a lot of useful information and helpful people answering questions, whether newbie/beginner questions or advanced stuff. Check out the EF and L2S-related tags:
Did I miss something?
The above are just a handful of the resources available, but should be good starting points. In all the blogs and forums I have linked to you will come across links to hundreds of other resources with useful information.