Of course this is not a new notion; over the past few years numerous alternatives have appeared, from the nascent NoSQL movement, to columnar databases, to massively parallel models. Many of these require trade-offs of some sort, but they are increasingly popular, particularly for specific applications. The key, though, is that most of these options deal only with traditional "structured" database data.
On the other side of the equation are traditional search engines -- much newer than the relational database, and focused on pure unstructured (text) content. Search engines typically can scale, but ease of use is a question. Many older examples require all the hardware needed for the future, to be available from the very first moment of operation, and adding hardware or moving content around for any reason can be costly and painful.
UIA offers the ability to store all kinds of information -- structured data and unstructured text -- and scales linearly, using the "shared nothing" model. Leading UIA platforms have focused on "ease of scale" through features like "waterfall scalability" wherein servers are loaded with information until they reach some performance limit, then more are added -- seamlessly -- without the need to re-index or move data around.
Over the next few years as we learn the true extent of the "data deluge," being able to scale simply and quickly across any sort of information boundary will be a major advantage.
Most major enterprise search conferences have at least one major session on security. Managers who attend are sometimes frightened to hear about things like "late binding" and "hybrid models" and discussions about security breaches that sometimes occur when documents are being reprocessed to reflect permission changes. These are serious issues that simply don't exist over on the "database" side of the house.
The reason is simple: databases solved the security problem several decades ago -- the "right" (or elegant) way. User and group permissions, or access control lists (ACLs) are stored in tables, the end-users' credentials are added to the query that is ultimately sent to the database, and the results contain only the information the user is authorized to see.