I think a lot of commenters are missing the point. It's not a question of whether the joke was funny or not. Humor is as subjective as beauty. Some people don't think any practical joke is ever funny, and some people can't get enough of them. We will never answer the question “was this funny or not”.
The real question is: was this a smart move? Was the guerrilla marketing buzz generated worth the possible alienation of some of the site’s users? And more importantly what does this do to their brand? What does Slideshare want us to think about their brand? Do they want to be the LinkedIn of presentation sites, or do they want to be the MySpace? In that light, I think that this was not a very smart move. For me personally, it makes me think that Slideshare is a little frivolous and not entirely professional. It makes any information from SS slightly suspect in my eyes…maybe only slightly, but do you ever want your brand to be considered even slightly suspect? If you think that makes me a humorless dolt who ‘needs to lighten up and take my self less seriously…” well so be it. I guess we’ll have to agree to disagree. But I have to say that messing with your brand image in such unstable times is risky at best.
What do you think?