If you're getting a 450 when trying to publish to your blog, retrying repeatedly does eventually work. Really.
But it's not reliable.
I just got my friend on IM, and she tried. And got more errors. And I tried for her. And got more errors. I tried 12 times or so (and didn't count). And still more errors.
But this was after I posted 3 or 4 notes in Blogger Help and Blogger Forum advising folks that it does work - really. And I'll bet some of them are blessing me, for telling them to retry. And others are cursing me.
But I know that it does work. Just be patient, and persistent.