I am writing this current post from my couch on my phone using the open source wordpress app for iPhone. Here’s my review of the app: sweet.
It’s very easy to use, and it has a great and simple interface. You can manage multiple blogs in a very intuitive and classicaly simple wordpress setup. If you are looking to manage your blog on the go (for some reason, I don’t really know why) wordpress for iPhone is the way to go.