Change This has a new manifesto up called The Six Laws of the New Software that's worth a read if you're in a position designing software. It's not that the manifesto points out anything new, but rather that it very clearly articulates the need for simple, easy-to-use software designed iteratively based on market needs. It'll probably only take you 5-10 minutes to read the article.
If the manifesto perks your interest in learning new ways to design software, you might take a look at the book "Agile Project Management: Creating Innovative Products" by Jim Highsmith. It's available on Safari, if you happen to subscribe to that service.