Turbo.264 HD software has been updated, offering full OS X 10.8 (Mountain Lion) support.
You can download version 1.2.1 (1604) here:
http://edgedownloads.elgato.com/turbodownloads/support/turbohd_121_1604.dmg
You can download version 1.2.1 (1604) here:
http://edgedownloads.elgato.com/turbodownloads/support/turbohd_121_1604.dmg