AFAIK, the only article on this is that below:
http://www.symantec.com/docs/TECH197771
This is the only one that actually refers to SEE rather than PGP (as posted earlier). I must admit though, objective observation seems to indicate that SEE is no longer being developed in favour of furthering PGP instead.
I'd recommend you contact Symantec directly (your account manager if you have one) for further details on the future of SEE.