These reference sites that might help you:
Wikipedia: http://en.wikipedia.org/wiki/Language_integrated_query
CodeProject: http://www.codeproject.com/KB/linq/
LINQ Video: http://windowsclient.net/learn/videos_LINQ.aspx , http://www.asp.net/learn/linq-videos/
LINQ Article by Anders: http://msdn.microsoft.com/en-us/library/bb308959.aspx
LINQ at MSDN: http://msdn.microsoft.com/en-us/library/bb397926.aspx
LINQ Project Home page at MSDN: http://msdn.microsoft.com/en-us/netframework/aa904594.aspx
LINQ FAQ: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=307705&SiteID=1
Step by step…
Introducing LINQ – Part 1
Introducing LINQ – Part 2
Introducing LINQ – Part 3
Introducing LINQ – Part 4
Introducing LINQ – Part 5