An 'industry' pattern appears to have emerged which builds a discovery layer over resources available from the library (or from a group library service, at the level of a state or a consortium for example).
Three characteristics come to mind. First, there is an attempt to provide an integrated discovery experience over multiple resource types/workflows: bought materials (books, CDs, etc), licensed materials (A&I databases, ejournals, etc), and institutional digital materials (digitised special collections, for example, or repositories of learning and research materials). Second, this 'horizontal' discovery layer is separated from the 'vertical' management systems which may manage those resources: the 'integrated' library system, the variety of systems which manage licensed resources, repository infrastructure, and so on. And, third, API access may be provided.
Various issues are being addressed as this model becomes more common. One that is interesting, I think, is that it will show how the three categories of resource I mention above - bought, licensed, and digital - have quite different dynamics in our systems and services.
Think, for example, of a distinction between outside-in resources, where the library is buying or licensing materials from external providers and making them accessible to a local audience (e.g. books and journals), and 'inside-out' resources which may be unique to an institution (e.g. digitized images, research materials) where the audience is both local and external. Thinking about an external non-institutional audience, and how to reach it, poses some new questions for the library.
Or think about the relationship between the 'locally available' collection and the 'universal' collection in each case.
* For bought materials (books, CDs, ...) the library provides access to the locally available collection - the materials acquired for local use - and then may provide access to a broader 'universal' collection through Worldcat or another resource.
* For licensed materials, access is first through the broader 'universal' level (in various databases) before checking for the subsect of locally available materials.
* For institutional digital materials, access is provided to local repositories but this will not typically be backed up by access to a 'universal' source for such materials (although, one can see attempts to do this, as, for example, where an institutional repository expands a search to Scirus).
Of course, if one thinks about other discovery/disclosure channels (Google, for example), these three collection types also behave differently. That is a topic for another blog entry though.