The Slane Castle rumour has actually appeared in the irish press. I too am sceptical about a band who hasn't toured europe in 6 years, filling a venue that size.
But, heres a thought. Maybe pj won't be playing euro festivals after Roskilde, but as an alternative way of making a euro tour profitable, are maybe looking at linking up with 2 or 3 other bands for a couple of big gigs? Foo Fighters, Audioslave, the Pixies maybe for a couple of shows in Dublin and Amsterdam
The venue would be full then, the cash would roll in, but it wouldn't be a festival as such.
Just a thought.

Sorry, there are way too many rumor threads and no good basis for them.