In re: it's closed – yes, but, in at least one sense it's actually infinitely open, and more open than any phone before it.
It has a fully, 100% desktop-compatible, web browser – Safari.
This means it _doesn't_matter_ that you can't run MS Office on it – you should be able to run Google Docs just fine. And who cares if you can't run your little Atom API blog posting software on it – you can just log right into Blogger. But what if I want some kind of interactivey kinda application? XmlHttpRequest, baby! That’s “Ajax” to you less-webdev-oriented people.
This is all presuming that Cingular doesn’t neuter it by forcing everything through some aggressive kind of aching proxy, which most carriers do to save bandwidth. If they don’t this device could _really_ be revolutionary. You can develop a site for the always-connected Desktop, and have it work nearly 100% with the iPhone! How cool would that be?
Edit – considering neutered web-browsing experiences – my shitty Blackberry browser truncated the post when I went into Blogger to move it from Draft to Post. See? I want an iPhone.