I'm certainly no pro either. But I am very involved in Physics/comtech in my school. It's currently completely unavoidable that lag will be introduced (to the best of my knowledge). In a Internet connection, lag per transaction is much greater, but it will make far fewer transactions.
The speed of electron info transfer is VERY close to light speed. BUT an electron will quickly dissipate, than they must connect it up to another switch. Each transaction introduces lag.
The added lag difference will make no difference in a long distance data transfer, but will be detrimental in a short distance transfer.
That is the limit of what I know in the matter, and am not sure if anyone knows anything else, more specific to Lightpeak about it.
In the meantime I suggest we spread the word that Light peak may not be the be-all-end all solution it is currently pinned up to be.