Article can be found here: http://blogs.vbcity.com/hotdog/articles/8858.aspx

The new Linq functionality is great and easy to use. Enough tutorials exist on how to use the Linq syntax and on both DLinq and XLinq as well. However when you want to implement your own Linq source, pickings are slim. The ones that are available use the IQueryable interface. However, before that interface and seemingly at the heart of Linq is the 'Query Expression Pattern'
In the following article the basics of that pattern are explored and hopefully provide some insight on how to easily extend on the vastness already provided by Linq: http://blogs.vbcity.com/hotdog/articles/8858.aspx