Multiple instances of the DCG is a common request from users. The trouble is, it's a devil of a job to set it up to work properly in the majority of likely use cases. At the moment, I'm waiting for the release of WP 2.9 which is supposed to bring significant changes to media handling in WordPress. This may well simplify the work I need to do. If it does, multiple instances capability will be re-considered.
So, did 2.9 make things easier?