Mark Pilgrim explains how to make the Movable Type publishing system automatically display off-site links in a different style than in-site links. Is this something news sites should be doing? Would users benefit from a knowing which links take them to other sites? Rebecca Blood has done this for a while now, but I don't think it's particularly helpful on a blog, where most links are external anyway. And using three, maybe four, different link colors (in-site link, off-site link, visited link, link hover) on the same page could get confusing quickly. My opinion: This is technological overkill.
UPDATE, 2:45 PM ET: Steve Outing suggests this could be a good way of distinguishing between paid and free content. I still think things would get confusing quickly if sites started throwing around three different link colors; unless there were a Web-wide standard for these colors (which is unlikely), users would have to relearn the color scheme for each site that used it. Not to mention color-blind users and users of alternate browsers wouldn't be able to make the distinction. A good solution: Use images to distinguish paid content, as Economist.com does.