A Snipsly user brought a good point to my attention. When you update a post on a different day from which it was first written the URL will be changed.
This is because each URL has a post date included in it. The URL looks something like this:
http://Snipsly.com/2010/04/01/your-article-title
Google has said that they would like an easy way to know when exactly a post was written. This doesn’t necessarily have to be in the URL, but it is a common structure for posts (especially on blogs).
Why does this matter to you?
If your article is ranked number 2 on Google and then you update that article the search engine will then take traffic to a 404 or “article not found” page. Why? Because you updated the article and it now has a different URL.
I will be looking into a redirect meathod to solve this problem. However, you can be sure that Google will correct the issue over time.
Helping people make money and solve problems. 
If the URL changes every time an update is done is it best to do nothing regarding tracking URL Channels, or should the old URL be deleted and the new URL be added to the URL tracking??
I’ve had the feeling from just reading as to how Google does page-rank that the length-of-time an article is posted adds to the overall formula for page ranking. Is this true?
Or, is it best not to update anything, do the update as a completely separate post and link to the original article?
I don’t use the date in my blog post URLs so I never noticed this before. Very interesting. I think I’ll stick to using the title words.