Sorry I'm a bit late joining in on this thread but I'm surprised no-one has mentioned Lucy Kaplansky and Stacey Earle. Also, in the UK Kate Rusby has a lot of "street cred" and although she does mostly traditional stuff she has written a few songs herself. (At least one of her CDs has been released in the USA by Green Linnet records).

Billy Bragg is also a good source - if you don't know his music it is a bit "folk-punk" but he has also recently "collaborated" with Woody Guthrie (i.e. finished songs Woody was working on in his last years). I think the album is called Mermaid Avenue or something similar.

Ps. I'm almost as old as Christy Moore but I haven't stopped being a teenager just yet.