I have a lot of blogs hosted at blogger, and say if I wanted to post an interesting link on all of them, it would be easier post the link to all of them at once. I know of a Firefox add-on called ScribeFire that allows you to post to your blog without actually being at Blogger.com, but it only allows you to post to one blog at a time.
I can see a use for it but surely you would want to change the wording a little? Would that not class as duplicate content?
Use posting through email feature of blogger.You can email same content to numerous email addresses.For this go to setting> email> mail-to blogger.