See sig. The easiest way to to it:
Write a post with
Spintax.
Pull it as an RSS feed to your other 100 blogs.
Profit.
Also if you install CyberSEO at your recipient blogs, you will be able to additionally spin the posts on the end side using your own synonym table or these spinner services:
WordAi,
TheBestSpinner,
SpinnerChief,
SpinRewriter,
SpinChimp,
ESpiner. Plus to that, the posts can be automatically translated to over 100 languages. They can be mixed with additional content etc.
I believe you won't find another plugin with all these features.