I understand this is more than a question than an idea, but bare with me for a sec...
I read that you guys are hard at work on 2.8, which you hope to tackle much of the media management hassles that still cripples overall functionality.
Well, I'd like to throw my 2 cents on this.
Keep everything in a library like you have, they are resources.
They should be able to be attached to as many items as you wish.
This means that attachments, and resources are separate.
Essentially an attachment, is simply an association of a resource with a post.
Keeping this separate eliminates any conflict with where and what the resource is doing.
There should be a way to retrieve all resources associated with a given item.
This should be similar to list_pages, or list_categories versus get_pages, get_categories etc...
You should be able to do the same with a attachments.
Sifting through the post's content for information is a NO NO back to the stone ages.
If you start with the correct materials and architecture you can construct anything you want more easily.
Think of possibilities of post thumbnails, category thumbnails, link thumbnails.
Think of being able to associate ANY NUMBER of resources, to any piece of information on the site. (or at least anything that is also an instantiated class).
Think of having resource templates, where coders could use geshi, and musicians can use media players, and photographers can use images.
This kind of resource formatting and filtering could and should be done within a THEME, not with 100 different combinations of plugins. (that's stretching a bit, sorry)
I realize this is going to the CMS side of things, but I just wanted to say this...
I just finished up my LAST site in the bloated app Joomla, I never want to see Drupal again, RIP Mambo, and need I say more with the quality of the rest out there?
LONG LIVE WORDPRESS!!!
I believe it has the potential to be the very best of a everything. Including a CMS.
Think about it....
I don't care if it started as a Blog engine.
What is a blog? It's a @#$# website!
What do you need to manage a website?
WordPress is great... and yet I believe it still has so much more potential.