Matt is correct. However I am reading that there are enough differences in the snow leopard frameworks that are causing some applications problems. Artpro 9 will give you problems with OSX 10.6 but Artpro 9.5 will work fine.
There is information about OSX 10.6 Snow Leopard compatibility on EskoLink.com.
EskoLink is a customer/dealer only website that provides information on products, upgrades, additional technical documentation, white papers, hot fixes, etc... and a view of your past and present service support calls with their status and resolutions. It's a great resource.
Here is the link: https://eskolink.esko.com/Link/site.aspx?p=1934&NewsID=634
You do need be a licensed owner of EskoArtwork products. If you have any problems or questions about getting on the site, please call your support line.