You might run into an issue with your web site one day and find that Google may remove your web site from its index. What can you do to address this issue? Depending on the issue you encounter, there are several different options.
If the problem is a result of a technical issue with your site (URLs not crawlable because of a server issue or coding problems), you don't need Google to reconsider your site for inclusion since Googlebot will crawl your site repeatedly until the issues are resolved. In other words, reconsideration requests are only needed when you actually did something bad that ticked off the Google gods.
That leads me to my next point -- or the one that Googler Susan Moskwa refers to. What happens if you lose your rankings in Google all of the sudden? A lot of people think that if their rankings drop, they're been penalized and think it's an appropriate time to send Google a reconsideration request. Usually, these traffic drop issues are more in your control than you think.
Forum discussion continues at Google Groups.