BeamItDown, the makers of iFlowReader, one of the App Store's most popular e-reading apps, are pretty mad at Apple over their new policy to take 30% for any e-book sold. Mad enough that they're shutting down on May 31st:

The crux of the matter is that Apple is now requiring us, as well as all other ebook sellers, to give them 30% of the selling price of any ebook that we sell from our iOS app. Unfortunately, because of the "agency model" that has been adopted by the largest publishers, our gross margin on ebooks after paying the wholesaler is less than 30%, which means that we would have to take a loss on all ebooks sold. This is not a sustainable business model.

This new policy puts Apple and iBooks at what would appear to be a very large advantage over other publishers. Not much need to take 30% from yourself unless you're trying to work the books somehow, eh Enron?

They want all of the eBook business on iOS and since they have the unilateral power to get it, we are out of business and the iFlow Reader is dead. We put our faith in Apple and they screwed us.

If you bought e-books through iFlow, it's recommended that you back them up before the end-of-May deadline. Or else... [iFlowReader via CNNMoney]