I thought i'd just share this with other users:
It turns out that whenever I leave my MOTU 896HD firewire audio interface connected, the utility doesn'n find any Eventide devices connected to the computer at all. When I disconnect the firewire interface, it works without problems. I'm on a Macbook pro with OSX 10.5.8.
Maybe other users can reproduce this problem and, if so, eventide could possibly include this in the sticky post on problems with Update Utility?