A few days ago I posted a link / observation of LINQ-to-Javascript a.k.a. JSLINQ.
Ajaxian just pointed out a new project called LINQ-to-JSON that is more LINQ-like. One would use JSLINQ for working with any type of arrays in real Javascript. The LINQ-to-JSON solution looks like a truer LINQ coding experience; however, I can't tell if it's actually for Javascript or JScript.NET, the latter of which is not web browser Javascript and only runs in .NET. I'll check it out further but wanted to raise my eyebrows first. :P
http://james.newtonking.com/archive/2008/02/11/linq-to-json-beta.aspx