The gorillas are Amazon and Apple: Macmillan is Fay Wray. The iPad pricing model is what triggered this. Amazon really wants to keep control of ebook pricing. Personally, I have little love for Amazon who are (among other failings) anti-union and compete in the market they make are notoriously monopolistic. While I think Apple's model is a good bit better for readers and authors they're hardly saints. Bottom line: it's a conflict over control of ebook distribution, and there aren't good guys, only less-bad guys.

Commentary:
Charlie Stross.
Making Light.
Cory Doctorow.
Charlie Stross's links page.