External SATA PM (Port Multiplier) Enclosure w/ Mac Mini I'd love to use one of the new Mac Mini Server models as a backup server, but need a lot more space.

Has anybody tried attaching a port multiplied eSATA enclosure to the Mini? This is the one I'd really like to work: http://www.firmtek.com/seritek/seritek-5pm/

I've read a few things that imply that the system controller in the Mac Mini supports it.
No, the SATA the Mac Mini does not support port multipliers. Technically the MCP79 in it can support port multipliers, but either the driver or the firmware does not enable it.