Bob's LinkedIn profile shows praise from colleagues who gave him credit for ensuring successful releases of complex application suites at AOL, as well as his being recognized as a "visionary" with energy and intensity, while at RedHat. Bob is also a patent-holder for his development of temporary digital certificate proxies that can be used for a specific amount of time.
The Obligatory "First Tweet" from the Mothership.
As Twitter's Web site and activity become more critical in the way the planet is communicating, so to will its need increase for security to protect that which is private to remain private, and enable accounts to be secured. It's also not unexpected that the company's core offerings will get increasingly complex - maybe not to the level of AOL Communicator, but expanding nonetheless.
We should be seeing what Bob will be bringing to the Twitter team over the next few years, or just keep tabs on his updates at @boblord.