I gave Mobile Blogging via SMS a trial run a few moments ago and am not pleased with the result. Unfortunately, if the post is lengthy it will not be seamless.
Longer messages are broken up into several short messages which post to the blog as separate posts. I am not completely knocking this method of blogging...you can always type a sentence or two, but who wants to read that? Then there's blogging via a mobile browser; I'll try that next.