If the system was ever adopted widely (which I presume the founders desire) I would imagine that spoof posting would be a huge problem if someone could pull it off.

I suspect blackhat SEOs would be all over it.

All of the black hats who want to abuse numerous holes in your browser of choice?

They wouldn't necessarily even have to get you to click on a link. There have been numerous attacks against image processing libraries.

Actually, I hadn't read this comment! XD

I don't think blackhats would be all over it, the links are completely invisible to a search engine...

Maybe Smear Campaign artists might take to it. Or spammers...

I'm not too familiar with Posterous, are all links nofollowed? Can't you post arbitrary HTML to your own blog?

Or people trying to prove a point, check the front page :P