We've recently implemented a SAN for a client to address the need for a second storage tier. The system presents storage to VMware hosts for use with Windows and Linux virtual servers, and is intended to provide capacity for archive data sets.
In this instance, we deployed an iSCSI AssuredSAN from Dot Hill, and it does exactly what it says on the tin: Smart. Simple. Storage. This affordable platform has successfully freed valuable capacity on the advanced, tier-1 storage arrays, thus extending value and lifespan whilst intelligently managing costs.