George Jardine, one of the original product managers for Lightroom does wonderful tutorial videos about Lightroom and Photoshop. They are very well done, very detailed and very useful. He has made available from his web site a video called "A Few Thoughts on Black and White Conversion... Past and Present." If you leave your email address he will send you a link to the page.

An abbreviated print version of the video is available at Digital Photo Pro.

Julieanne Kost demos how to convert to black and white in Lightroom, make adjustments with the Adjustment Brush ( including adding color) , adding a vignette and grain.