Yes it's true.
When I got home last evening they were showing Setanta Ireland on Channel 21, where they previously had the local sports channel. After midnight it showed college basketball from the States on NASN.
Looking at its TV listings, Setanta Ireland shows a mixture of Irish sports, (Setanta Cup, NFL, schools rugby etc) and American sports. I'd imagine that live RWC will be on Setanta Sports 1 and 2 only.
Chorus are now also broadcasting Setanta Golf, but it's not free.