I'm creating an integration for Opencart and WordPress as an Opencart module. It will allow you to add WordPress specific information into Opencart blocks. I'm calling it WPOpencart or WPOC for short.
ie. Latest Posts, List of Post Categories, Posts that are in a category, List of bookmarks, wordpress search box, archives and the navigation menus.
Once phase 1 of this module is complete I think I want to code it the other way around to get information out of Opencart and into WordPress - I think this integration would be more powerful than the previous & more flexible, and also because WordPress has so many more templates and plugins available.
The main goal of both of these integrations is to leave the underlying code of both packages intact, so that any existing wordpress and Opencart can have the other attached or detached at any time. No database or coding lock-ins.
And no, neither one of these will be an iframe implementation. I repeat NOT using iframes to retrieve content.