There's a lot of overlap between Viral Marketing (and disastrous consequences as mentioned in my Viral Marketing post) and Guerilla Marketing. That's because Viral Marketing is a subset of the much broader Guerilla Marketing, named in the eponymous book Guerilla Marketing by Conrad Levinson, the Creative Director of my personal hero and fellow Leo, Leo Burnett. The former makes use of atypical campaigns to generate talk about a produce or service, getting it to spread by word of mouth throughout the community. So in that context, the Adult Swim snafu was a form of Guerilla Marketing.
The latter, however, constitutes many subsets, Viral being only one overused variation. One of my favorite examples was when Dominoes began paving roads, fixing potholes, and superimposing their logos on the repaired pavement. It was brilliant and unorthodox, which sums up what all good Guerilla Marketing should be.
Because it is high risk, (see the Viral article for more on that) high reward, this style of marketing is best used by smaller businesses or smaller satellites of larger businesses, where the backlash is smaller and the prospect of success can make or break that business.
Some cities have actually passed laws preventing these types of campaigns due to the possible consequences, but the vast majority of Guerrilla Marketing attempts have given their businesses far more attention (and subsequent sales) to discourage this trend from slowing down anytime soon.
The takeaway? It's lucrative to be innovative. It's profitable to think outside the box. But study every angle, and look for flaws in your technique to mitigate the risk. And before attempting anything unorthodox, ask yourself: "Are we doing this because it will work or because it seems cool?" If you answered the latter, consider going with a more traditional approach before you wind up on the front page of a big city newspaper for all the wrong reasons.