As an example, on my way to the Sydney Oracle Meetup 'Expert' event I had a phone call from my bank. Apparently my credit card had just been rejected in a Australia Post office as a suspect transaction. Since I'd been on the train it wasn't me. The card was in my wallet too, so it hadn't been nicked. The card had been skimmed somewhere.
The suspect transaction wasn't above my credit limit. It's not like I've never used it in an Australia Post either (though never for the amount involved). It may have been an odd location, but I hadn't had any rejections on a recent holiday. In short, it probably wasn't any single factor that tripped the security wire, rather a whole set of criteria that marked it as suspect. Okay, maybe it came down to a suspicious employee of Australia Post, but this is a database blog not an episode of Law and Order.
There's a careful balancing act the bank has to perform (and it did it very well in this case). It has to, in the words of the article, "let the people play". It can't stop every credit card transaction, but has to look for rogue behavior. Its not something I've directly worked in, but I've done fuzzy algorithms for data matching. You add some points for one fact, a few more for another and at the end you get a resulting numeric value for 'how likely'.
That requires lots of logging of activity, and there's an increasing requirement to analyse these logs, sometimes in real time (or near real time) for those behavioral factors. Hadoop seems to get some mentions for this form of analysis, though I'm sure there are other solutions in the NoSQL world. I'm sure VoltDB would offer themselves up here too. My gut feel for this style of application would be some form of distributed data store.
There are rumors of an Oracle Hadoop Appliance which may or not be confirmed in a few weeks at OOW. That said, there have long been rumors of an Oracle Games Console, and I'm thinking of applying for a trademark for ExaPhone before Larry gets in there. Oracle do have a pedigree of dealing with vast amounts of data (anyone mention CERN ?) so it will be interesting to see how they play out in this area.