Wordpress - The Great Plugin Nomenclature Contest of 2011
SPARKS
(I was thinking Flames....but that's kinda negative in the interwebs world, no?)
Is there a way to not have to post 30 characters??
Crossposts.
Simple, easy, accurate. They are posts from another site, crossposted to this site. Also fits with the name of your plugin.
Generally speaking, it's best to use descriptive names from other contexts. A lot of people understand the idea of "crossposting", which is obviously why you picked the plugin name. For a post_type, "crossposts" makes sense here, and people will recognize it from other contexts they've used it in.