it is better if you prefix your identifier with a short namespace that identifies your plugin, theme or website that implements the custom post type.
For example:
acme_product or aw_product for products post type used by a hypothetical ACMEWidgets.com website
1More
How to Style Each WordPress Post Differently - 0 views
1More
Creating Custom Post Types In WordPress | Elegant Themes Blog - 1 views
2More
Practical Uses for the Post-Thumbnail Function in WordPress 2.9 - 7 views
1More
WordPress › Dynamic Featured Image « WordPress Plugins - 0 views
1More
How To Make Your WordPress Website Multi-Lingual | Elegant Themes Blog - 0 views
3More