I just downloaded a couple mobile blogging apps for iPhone that support the Blogger API. BlogWriter and BlogPress both have free trial versions, so I figured my first attempt to get things working would be with them. If I can't connect at all to blogspot, then it's no money out of my pocket for the experiment.
A word from the not-so-wise: look up your username and password when setting up something on the iPhone. I could have posted this 3 hours earlier if I hadn't been entering the wrong password to my gmail account. Thank you, Firefox, for letting me forget.
After the 3 hours of learning about XML-RPC, the nasty guts of the original Blogger API, and how to integrate with Drupal/Joomla, I finally have two working mobile blogging apps.
BlogWriter seems to be aimed at a larger community of bloggers. It supports Blogger, WordPress, and anything that can speak the Blogger API at a custom URI.
BlogPress, despite being a portmanteau of Blogger and WordPress, only supports Blogger. The configuration is simple (provided you know your password), but it does require both Blogger/BlogSpot and Picaso credentials. They're the same now, though, and thankfully the app pre-filled my Picaso login information.
BlogPress also appears to be able to work with drafts; I don't yet know I'd they're only local to the iPhone or if it's integrated into the main Blogger web interface.
This just in: BlogPress doesn't turn sideways. Really a bummer because the iPhone keyboard is much easier to use in landscape orientation. Spellcheck and autocorrect can only do so much.
That's really all I have to compare until I actually use BlogWriter. So far, though, it looks like blogging on the iPhone is definitely doable, even without Google's SMS and e-mail hacks.>