For those of you on subscription, the Inventor 2011 Subscription Bonus Pack includes API functionality for AEC Exchange. (In Inventor it is still referred to as AEC Exchange but the API refers to it as BIM Exchange since it will be called BIM Exchange in the future.) The API provides the same functionality that you have through the user-interface; you can define and edit connections, define and edit the definition of a component, and output a component as an .adsk file.
This enhanced functionality is part of the subscription bonus pack, but the API documentation was not updated to reflect this new functionality. Below is a link to documentation for the BIM Exchange API.
BIM Exchange API Documentation
Be sure to read the introduction, particularly if you are using a .Net based language. There is also a small sample program at the bottom of the document.
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