I read the GPS unit TomTom will be offered as an option in the 2008 Yaris according to GPS business news. Here's a link to the story:
TomTom enters Toyota Yaris' dashboard
This overseas member:
New Member from Switzerland also has the unit in his Yaris.
ECLIPSE by Fujitsu Ten has the AVN-2210p in-dash head unit that includes a detachable TomTom GPS unit, pretty clever if you ask me.