I'm not a big fan of the various mac rumors sites, but there have been several reports of new Minis being imminent (based on hardware device IDs referenced in new Mac OS version).
The device IDs were in reference to the Nvidia GPUs. So, if you're interested in HDCP or HDMI, you probably want to wait for a while for the refreshed Minis.
Who knows, Blue Ray is not outside the realm of possibility either. I love my current Mini (old core duo 1.66GHz), but blue ray would be enough to get me to upgrade.