While IBM could use secure containers to deploy applications to users' devices, enabling it to wipe just the container and not the entire device, that option hasn't been used so far, Horan said. She is looking forward to the broad availability of mobile hypervisors that would allow devices to run separate OSes and related applications for corporate and personal use.
Another dilemma facing enterprises, including IBM, regards whether to develop and maintain separate native applications for each mobile platform, or focus on browser-based applications that can be written once and deployed cross-platform. The emerging HTML5 standard, with its richer capabilities, is helping spur interest in the latter option.
HTML5 is "definitely a direction we've been focused on," Horan said. "I don't want to have to maintain all these devices." However, she said, "I'm not sure whether my users are going to find that acceptable."
IBM's recent acquisition of Worklight, which has an array of mobile application development technologies, should also help Horan's teams, she said. "It was a gap in our portfolio."
Not every challenge for Horan in managing IBM's mobility strategy is so technical. Its presence in 170 countries makes offering a managed corporate carrier plan complicated. "Sadly, we have to have a contract in every country, pretty much," she said.
That said, a broader move to mobile phones could result in some cost savings for IBM: "How do I make the mobile phone the only phone for the [employee] and then get rid of my office phones?" she said.
However, a full-blown global push toward mobile-only phone service at IBM is ultimately dependent on when cellular service reaches a satisfactory level in all locations, Horan said.
BYOD in general is still a fairly new concept, but some major debates have already cropped up over how to manage and govern such projects, said Dion Hinchcliffe, executive vice president of strategy at "social business" consulting firm Dachis Group. The prominence and scale of IBM's ongoing deployment is thus worth paying attention to, especially its approaches to management and policy.
There's also the subject of how BYOD programs should handle device procurement, Hinchcliffe said.
Hinchcliffe cited the example of one CIO at a large global corporation, which he declined to name, who gives each employee a "BYOD budget," a fixed sum of money that they can use to purchase the devices they want.
"That's a very enlightened perspective," he said.
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