Search Engine Watch has a post about the first documented case of being banned on Live.com for doing link exchanges.
Your site is acquiring links through posting to or exchanging links with sites unrelated to your site content. Techniques which attempt to acquire unrelated spam links in order to increase ranking are considered spam and your site has been excluded from our index as results. Please contact us once you’ve removed these links and we will reevaluate.
Google has manual site reviewers to prevent manipulation of the search index. Since majority of the traffic to a site comes from the first 30 results, there’s suspicion of a 30 position penalty.
To avoid any appearance of a reciprocal link exchange, you can perform three-way link exchanges. This, of course, requires you to have multiple sites to offer a link from. The best way to ensure against any possible future issues with link exchanges if you are still determined to do so, however, is to request RELATED links only. Thus a wedding site may request links from wedding photographers, caterers, limo services, etc. Getting link-backs from any website under the Sun is sure to hurt in the long run if it hasn’t already.