It's only more secure if it implements the same security measures (encryption, key based access) as current wireless (okay, if the light is infrared it may be stopped by windows.
I don't think it will be a big contender for wireless though. The killer feature of wireless is that you don't have to drill holes in your walls to have network connectivity in the entire house. But if the network is optical, it will essentially be limited to the room where the base station is. Personally, I'd stick to my trusty old wires then. Reliable, secure, fast and low-cost, what more do you want?