Accelerating enterprise adoption of mobile platforms will lead to more security threats on mobile devices.
Adoption of mobile platforms, check. More security threats, not yet. I think I missed the time-scale (I'll have to decide if this one goes into 2009 predictions or if it's too early). With the opening up to a multitude of developers and applications, and even more open, might become an issue.
Hard-drive encryption on the desktop will continue and spread to the data center.
About 50% on this one. Laptop encryption and desktop encryption are becoming more mainstream. Laptop ended up one of the top three security initiatives funded in the enterprise in 2008. Data center servers are not following just yet.
Network-access-control sales will continue to fall short of the hype.