IT convergence creates high anticipation and anxiety. New people entering physical security is one of the most emotional. The security systems market is a lot like Las Vegas - growing quickly, few of us are actually natives of the security industry; Over the last decade, most of us have migrated from IT (including myself).
A lot of the debate centers around whether IT will save or destroy physical security. Certainly Cisco is the most visible representation of this issue but the same concern arises each time major new IT companies or executives enter the space. This week, traditional leader Pelco hired an executive from Nortel, last month a video surveillance company hired an executive from Apple. By contrast, IP market leader Axis has recently hired a string of security system executives from Lenel, Honeywell and Panasonic.
Not Primarily a Conflict Between IT and Security
From reviewing dozens of video surveillance companies, I think the perceived conflict between IT and Security is misleading. While there is certainly tension among companies and inside of companies, that's usually not the root cause.
Security vs. Other Business Units
Security is obviously different from IT but the bigger difference is between security and other business units - marketing, accounting, operations, etc. Most (or all) of the other business units that IT serve are fundamentally far different than security. Bringing in expectations and practices that work in other business units tend to fail badly in security.