With the increasing popularity of the EKM feature in SQL Server 2008, more vendors are adding their support for this great feature.  I'm very happy to announce that Arx has just announced their releaese of their EKM provider dll:

http://www.arx.com/about/PR/PR-PrivateServer-HSM-Secures-Sensitive-Information-for-Microsoft-SQL-Server-2008.php

I'll keep you up-to-date with future vendor support. 

Il-Sung.