I have gone to an interview at toyota and was very surprised the interviewer asked me questions about Linq. I can't believe Linq is being used by these big corporations. Do you guys use linq where you work at?
I work at a very large corporation (>400k employees) in a small group. We use Linq and Linq2Sql in our data tier. As a small group we get to make most of the decisions on what technologies we use.
Past my technical manager, no one cares specifically what technology we are using, as long as we get the job done.
Yes. LINQ, while fairly recent, is a very solid part of the .NET framework and languages. It cuts down on things that would've taken extensive coding or extra lines of code. In addition, in many scenarios the readability gained from using it makes it worth it over traditional approaches. Sure, there are scenarios where it can be overused and abused, such as in the the code golf questions where terse answers are desired, but it should be used appropriately in a balanced manner.
If you are under the impression that it isn't mature or can be a performance killer, it depends on where it's used. Sometimes the traditional route is more performant, other times it isn't. Most of the times the fluid style gained from LINQ, even if there's a slight performance drop, won't affect much since there's no need for early optimization. For a good read on LINQ to SQL performance, take a look at Rico Mariani's series of blog posts.
I use LINQ to Objects all the time. I don't think you can be a "modern" C# developer without knowing how to use LINQ properly.
Linq to Sql or any other ORM with IQueryable support is a different story. Yes I've used it but I don't think its required... yet...