If you've created folders within your Assets Library, you can now add items directly into those folders via the popup in the WYSIWYG rather than having to go to the Assets Library to do it.
When adding the asset via the popup, if any folders exist then it'll present an option to choose the folder you want to add to.
This should make it much easier to keep your assets library organised!
FYI it's perfectly safe to move Assets around into different folders even after you've added them. Unlike with Content, if you move an Asset into a different folder then the URL doesn't change, and so any existing links to that asset will still work just fine.
Joe - Voice Admin