Okay, one more. Google cranked out seven new Webmaster Help videos feature Matt Cutts (and in some cases, other Googlers) talking about various types of webspam.
So far, we've looked at three videos about unnatural links, one about thin content, one about user-generated spam and one about pure spam. You can find them all here.
Finally, on to hidden text and/or keyword stuffing. This, like much of the content found in the other videos is pretty basic stuff and pretty common SEO knowledge, but that doesn't mean it's not valuable information to some.