The deal isn't really about Rojo (which Six Apart plans to sell off, keeping a minority share). It's about Alden, who will now run Six Apart's Movable Type division (one of the company's oldest money-makers), according to GigaOM blogger Liz Gannes.
Rojo co-founder Kevin Burton says Alden won't have much of a commute, since both companies are in San Francisco's startup-heavy South Park district. (We hear GigaOM founder Om Malik heard about this deal when he saw Alden and 6A CEO Barak Berkowitz outside 6A's office.)
TechCrunch blogger Michael Arrington broke the news this morning; he guesses Six Apart paid $5 million. That'd be a terrible deal for a company that took $3.5 million from investors since its 2004 launch.