Multi-blog Posting

I am using WP on multiple sites at the moment and two of them are mine. One is on my laptop (mostly to share with coworkers and to keep a diary of work stuff) and one is my live site http://www.vminc.net. I end up using my local blog a lot more often then my public one. I would love to be able to have entries submitted to multiple places. There are entries that I end up placing in both blogs so this would be great.
I can create the Hack myself but I thought that this would be a great feature for advanced bloggers everywhere.
The most important issue would be security but that can be over come. just make sure that each blog is linked (aware of the other)This can be done two ways one have specific a URL registered for each blog or assign a key to each. The URL way is the most simple and the Key way is much more secure.
Tell me what you guys think and am I missing anything important inside or outside secutity.