[dsizzle]

I don't understand why you think this is a bad idea - 301 redirects exist for a reason. Redirecting to what the user probably wants is better than a 404 page.

That said, typically most people are going to find a site via search or clicking a link, which is why I think basically no one bothers doing this.

[wudu]

301 is "Moved Permanently". The content in question wasn't (necessarily) moved. If you control and know for sure that old URL was renamed to something else, then yes - 301 redirect is appropriate. But guessing and redirecting isn't that.