I ran into this quote at AmericanPapist, re. World Youth Day:
"In what is often seen as one of the most intensely secular nations in the world, Australia received a wake-up call..."
So much of the story of WYD in Australia reminds me of Denver's: the culture there seems pretty comparable to the American West's, the numbers were roughly the same, and I think there will be a similar effect on the local Church.
In the Archdiocese of Denver, the two local seminaries are bursting at the seams compared to 15 years ago, lay organizations like the Neocatechuminal Way and FOCUS (Fellowship of Catholic University Students) are thriving, and I know of at least two local priests that have gone on to become bishops since then, not to mention Cardinal Stafford's and Archbishop Gomez's advancement.
For me personally, it's been the gift that keeps on giving: I was kind of a punk kid when I went, and really didn't appreciate the significance of what I had been "dragged to." As time goes on, though, I realize more and more what an impact it really did have on me. For example, going to concerts and other (secular) gatherings involving lots of people in the same demographic as WYD later on really woke me up to the fact that the joy and love I saw on display there wasn't just because of the exuberance of youth; rather, it was the Holy Spirit at work.
For a really great personal conversion story related to WYD Denver, follow the link to Marcus Grodi's Coming Home Network.