Opus 10 provides full support for the Windows 7 Libraries system. Opus 9 provided support for Libraries by hosting the Explorer namespace extension, but Opus 10 supports Libraries natively, which enables full Opus functionality in Libraries.
In addition, Libraries are emulated under Windows XP / Vista, which enables those users to also make use of the Libraries concept (although of course on those systems, Libraries will only work inside of Opus).
Libraries are accessed in Opus using the lib:// path. Browsing to lib:// in a Lister takes you to the root of the libraries namespace, and all libraries can be accessed from here. You can also create and delete libraries from here. The member folders of a library can be viewed and edited by right-clicking a Library and choosing Properties (same as in Explorer).