The first line in the article "Rap Genius founder Tom Lehman says Heroku misled him and cost his company money."
I have to imagine they're involved based on the number of articles I've read about them over the last week. Their own article, tech blogs interviewing them about the article, and now the founder's picture at the top of this article.
Granted, the article is poorly written and seems to imply their involvement. But it explicitly states, near the end, that the law firm involved has yet to find any plaintiffs:
He’s spoken with one customer, who has since backed off. “That being said, I am in the process of drafting a complaint, in case their feet warm up,” he told us.
Furthermore, Tom (the dude pictured) commented in a thread above saying he didn't even hear about the lawsuit until Wired called him to interview him for the article. Consider putting away your "Jump to Conclusions" mat and joining us in the world of facts.