MDM software helps enterprises cope with all the devices that employees bring to work: their own smartphones, their tablets, their PCs. (In enterprise speak, that's a trend called "bring your own device" or BYOD.)
IT pros don't control these devices, but they still need to make sure that they won't introduce viruses to the corporate network and that they have access to corporate software. MDM software does this sort of thing.
There are quite a few MDM players out there, and it's not surprising that IBM would acquire one. One unique thing about FiberLink is that it was the first MDM player to support Google Glass, prepping for the time when employees bring them to work. Market research firm Gartner expects companies to be using Glass (and similar devices) big time by 2017.
Terms of the deal were not disclosed. FiberLink raised $50 million in 2003 from Technology Crossover Ventures.