A few weeks ago, we posted a comparison of ebook readers featuring, among others, the iPhone app Stanza [App Store link]. As Steve mentioned, Stanza works with nearly every ebook format, even Project Gutenberg etexts. I only used Stanza briefly to check it out and I can say that the UI was very nice. Additionally, the folks who created Stanza have an existing relationship with ebook seller Fictionwise. In fact, Fictionwise created an ebook store just for Stanza users.
This week, we've learned that Amazon has acquired the company behind Stanza. We can only assume that aspects of Stanza will make it into a future release of Kindle for the iPhone.