It seems Posterous fiddles with outgoing links so they are routed via viglink.com. VigLink is some kind of affiliate program.
This interacts with the NoScript plugin in a funny way. NoScript lets users choose which domains get to run JavaScript on their browser, and also has some XSS protection rules built in. If you disable the viglink.com domain, this will work as expected — no link redressing. But if you try to be a nice guy like me and allow the viglink.com domain to run JavaScript (hey its a free service…) the XSS protection will kick in and break the routing functionality, so users are left with a blank screen. Well, back to disabling viglink.com then.
