Eagle CAD and Sunstone
Our pcb fab partners up the road just released a set of design rule files (.DRU) files for use with the Eagle schematic and PCB layout editor. The design rules set allows Eagle users to consider Sunstone's manufacturing rules early on in the layout phase and that's a good thing.
Simply download, install and activate the design rule file and then Eagle will automatically let you know if your board layout will work or if specific areas need to be changed.
You can get the design rule file at the Eagle CAD website or directly off the Sunstone website at: http://www.sunstone.com/pcb-resources/Downloads.aspx. You can also download Sunstone's CAD software, PCB123, from the same page. Scroll down to find the design rules.