The X= Blog has posted the first of a two-parter on using the grayscale sliders in Lightroom.
The article covers how to convert a colour image to grayscale in Lightroom and how to use the sliders inside the develop module to best effect to alter the relevant brightness of just specific colours.
One of the more interesting things in the article is a list providing a rough indication of how each of the colour sliders will affect the image. For example, the orange slider has the biggest impact on skin tones, and the yellow slider can be used to lighten teeth and eyes.
Follow the link below to read the full article and look out for part two which will cover more advance techniques to use on monochrome images and some tools to make the task easier.