Endpoint Protection 11 is Symantec's corporate version while Endpoint Protection Small Business Edition 12 is for SMB. 

So far...version 12 is the newest.. I think...
http://www.symantec.com/business/support/endpointsecurity/migrate/index.jsp  

thanks..

Symantec Endpoint Protection Client and Manager Version List
http://service1.symantec.com/SUPPORT/ent-security....

And yes Nel Symantec version 12 is the latest one which is for Small Business servers

The Biggest Defference between the SEP 11 & SEP 12 is that SEP 12 does not use the IIS. Hence it is better alternative in Small bussiness server.

Why SEP 12 is for releasing since our SEP 11 still encountering lots of problem, does SEP 12 resolve all the issue of SEP 11?

As there are a lot of differences between SEP 11 and 12, hence it is not possible that SEP 12 resolves the issues related to SEP 11.

Also SEP 12 is specially designed for Small Business Servers and it is not an upgraded version of SEP 11.

As SEP 12.0 is for Small Business there is no Replication, FailOver, Load Balancing and Ad Sync.

Below is the link that will tell about Features, System Requirment and more

Link: http://www.symantec.com/business/endpoint-protecti...

In SEP SBE 12

1. No IIS - it's build on Apache -

2. No Application and Device Control

3. No Location Awareness

4. No Installation packages

5. Licensing (you will need *.slf file)

6. No SQL support 

7. - it's targeted for clients with less than 250 so nothing strange
.

SEP Small Business Edition (SBE) is intended as a parallel release to SEP 11, in much the same way SAV had a small business edition (which was license-based) as well as a corporate/enterprise edition.  Eventually there will be a SEP 12 (enterprise).  SEP SBE 12 is not intended to be an upgrade of SEP 11

do we have a TAT on the SEP 12 for enterprise?
what are the possible features?
thanks...