This is the function currently met by the FreeBSD Ports Collection. A Meta-based system could act similarly, but not be limited to a single OS variant or to add-on packages.
Definitive, mirrored repositories could be established, containing every significant release of every interesting package. Aside from being a convenient resource, this could serve as a precaution against loss or damage.
File usage and other information could be analyzed systematically, yielding subsystem data-flow diagrams, navigable descriptions ("What files are used by this package, how, and why?"), etc.
The archive could also help developers to examine and merge disparate package versions. Merging may be motivated by reduction of clutter (e.g., folding together similar ports), the need to support new environments (e.g., combining disparate ports to create a version with aspects of each), etc.
By preformatting (e.g., into HTML or PDF) and indexing the archived code and documentation, a repository could make these material conveniently available to all. This would be particularly valuable to administrators and programmers who wish to "look over" a package, prior to downloading it.
A Meta-based browser could allow examination of descriptions, documentation, code, and current configuration (if installed) of arbitrary packages. By tracking inquiries and accepting user feedback, the browser could also serve as a vehicle for information collection. (See Browser Notions for some browser-related user interface ideas.)
A Meta-based security audit utility could run on multiple OS variants, and even multiple machines on a network, using Meta's data abstractions and preference facility to handle portability issues.
By combining the local configuration status with package-specific information, a Meta-based utility could suggest and/or implement updates, tracking dependencies, local preferences, etc.